接上文 下面是一段示例代码

下面是一段示例代码

<code class="hljs xml has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"vertical"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/linearLayout1"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:gravity</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"center"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"50dp"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">ImageView</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/imageView1"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:src</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@drawable/logo"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingRight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"30dp"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_gravity</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"left"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_weight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"0"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">View</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/view1"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_weight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"1"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">Button</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/categorybutton"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:background</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@drawable/button_bg"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_weight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"0"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"120dp"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">style</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@style/CategoryButtonStyle"</span>/></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/headlines"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.HeadlinesFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right- 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li></ul>

下图是在横纵屏切换的时候的显示效果，我们可以看到这样可以很好的适配屏幕尺寸的变化。

weight是线性布局的一个独特的属性，我们可以使用这个属性来按照比例对界面进行分配，完成一些特殊的需求。

但是，我们对于这个属性的计算应该如何理解呢？

首先看下面的例子，我们在布局中这样设置我们的界面

我们在布局里面设置为线性布局，横向排列，然后放置两个宽度为0dp的按钮，分别设置weight为1和2，在效果图中，我们可以看到两个按钮按照1：2的宽度比例正常排列了，这也是我们经常使用到的场景，这是时候很好理解，Button1的宽度就是1/(1+2) = 1/3，Button2的宽度则是2/(1+2) = 2/3，我们可以很清楚的明白这种情景下的占比如何计算。

但是假如我们的宽度不是0dp(wrap_content和0dp的效果相同)，则是match_parent呢？

下面是设置为match_parent的效果

 

我们可以看到，在这种情况下，占比和上面正好相反，这是怎么回事呢？说到这里，我们就不得不提一下weight的计算方法了。

android:layout_weight的真实含义是:如果View设置了该属性并且有效，那么该 View的宽度等于原有宽度(android:layout_width)加上剩余空间的占比。

从这个角度我们来解释一下上面的现象。在上面的代码中，我们设置每个Button的宽度都是match_parent，假设屏幕宽度为L，那么每个Button的宽度也应该都为L，剩余宽度就等于L-（L+L）= -L。

Button1的weight=1，剩余宽度占比为1/(1+2)= 1/3，所以最终宽度为L+1/3*(-L)=2/3L，Button2的计算类似，最终宽度为L+2/3(-L)=1/3L。

这是在水平方向上的，那么在垂直方向上也是这样吗？

下面是测试代码和效果

如果是垂直方向，那么我们应该改变的是layout_height的属性，下面是0dp的显示效果

下面是match_parent的显示效果，结论和水平是完全一样的

 

虽然说我们演示了match_parent的显示效果，并说明了原因，但是在真正用的时候，我们都是设置某一个属性为0dp，然后按照权重计算所占百分比。

使用相对布局，禁用绝对布局

在开发中，我们大部分时候使用的都是线性布局、相对布局和帧布局，绝对布局由于适配性极差，所以极少使用。

由于各种布局的特点不一样，所以不能说哪个布局好用，到底应该使用什么布局只能根据实际需求来确定。我们可以使用 LinearLayout 的嵌套实例并结合 “wrap_content” 和 “match_parent”，以便构建相当复杂的布局。不过，我们无法通过 LinearLayout 精确控制子视图的特殊关系；系统会将 LinearLayout 中的视图直接并排列出。

如果我们需要将子视图排列出各种效果而不是一条直线，通常更合适的解决方法是使用 RelativeLayout，这样就可以根据各组件之间的特殊关系指定布局了。例如，我们可以将某个子视图对齐到屏幕左侧，同时将另一个视图对齐到屏幕右侧。

下面的代码以官方Demo为例说明。

<code class="hljs xml has-numbering" style="display: block; padding: 0px;  color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-pi" style="color: rgb(0, 102, 102); box-sizing: border-box;"><?xml version="1.0" encoding="utf-8"?></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">RelativeLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">TextView </span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/label"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:text</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"Type here:"</span>/></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">EditText </span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/entry"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_below</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@id/label"</span>/></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">Button </span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/ok"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_below</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@id/entry"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_alignParentRight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"true"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_marginLeft</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"10dp"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:text</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"OK"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">Button </span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_toLeftOf</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@id/ok"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_alignTop</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@id/ok"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:text</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"Cancel"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">RelativeLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute;  50px;  top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right- 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li></ul>

在上面的代码中我们使用了相对布局，并且使用alignXXX等属性指定了子控件的位置，下面是这种布局方式在应对屏幕变化时的表现

在小尺寸屏幕的显示

在平板的大尺寸上的显示效果

虽然控件的大小由于屏幕尺寸的增加而发生了改变，但是我们可以看到，由于使用了相对布局，所以控件之前的位置关系并没有发生什么变化，这说明我们的适配成功了。

使用限定符

使用尺寸限定符

上面所提到的灵活布局或者是相对布局，可以为我们带来的优势就只有这么多了。虽然这些布局可以拉伸组件内外的空间以适应各种屏幕，但它们不一定能为每种屏幕都提供最佳的用户体验。因此，我们的应用不仅仅只实施灵活布局，还应该应针对各种屏幕配置提供一些备用布局。

如何做到这一点呢？我们可以通过使用配置限定符，在运行时根据当前的设备配置自动选择合适的资源了，例如根据各种屏幕尺寸选择不同的布局。

很多应用会在较大的屏幕上实施“双面板”模式，即在一个面板上显示项目列表，而在另一面板上显示对应内容。平板电脑和电视的屏幕已经大到可以同时容纳这两个面板了，但手机屏幕就需要分别显示。因此，我们可以使用以下文件以便实施这些布局：

res/layout/main.xml，单面板（默认）布局：

<code class="hljs xml has-numbering" style="display: block; padding: 0px;  color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"vertical"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/headlines"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.HeadlinesFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute;  50px;  top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right- 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

res/layout-large/main.xml，双面板布局：

<code class="hljs xml has-numbering" style="display: block; padding: 0px;  color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"horizontal"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/headlines"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.HeadlinesFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"400dp"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_marginRight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"10dp"</span>/></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/article"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.ArticleFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute;  50px;  top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right- 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li></ul>

请注意第二种布局名称目录中的 large 限定符。系统会在属于较大屏幕（例如 7 英寸或更大的平板电脑）的设备上选择此布局。系统会在较小的屏幕上选择其他布局（无限定符）。

使用最小宽度限定符

在版本低于 3.2 的 Android 设备上，开发人员遇到的问题之一是“较大”屏幕的尺寸范围，该问题会影响戴尔 Streak、早期的 Galaxy Tab 以及大部分 7 英寸平板电脑。即使这些设备的屏幕属于“较大”的尺寸，但很多应用可能会针对此类别中的各种设备（例如 5 英寸和 7 英寸的设备）显示不同的布局。这就是 Android 3.2 版在引入其他限定符的同时引入“最小宽度”限定符的原因。

最小宽度限定符可让您通过指定某个最小宽度（以 dp 为单位）来定位屏幕。例如，标准 7 英寸平板电脑的最小宽度为 600 dp，因此如果您要在此类屏幕上的用户界面中使用双面板（但在较小的屏幕上只显示列表），您可以使用上文中所述的单面板和双面板这两种布局，但您应使用 sw600dp 指明双面板布局仅适用于最小宽度为 600 dp 的屏幕，而不是使用 large 尺寸限定符。

res/layout/main.xml，单面板（默认）布局：

<code class="hljs xml has-numbering" style="display: block; padding: 0px;  color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"vertical"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/headlines"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.HeadlinesFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute;  50px;  top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right- 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

res/layout-sw600dp/main.xml，双面板布局：

<code class="hljs xml has-numbering" style="display: block; padding: 0px;  color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"horizontal"</span>></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/headlines"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.HeadlinesFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"400dp"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_marginRight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"10dp"</span>/></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">fragment</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/article"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.example.android.newsreader.ArticleFragment"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"fill_parent"</span> /></span> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute;  50px;  top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right- 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li></ul>

也就是说，对于最小宽度大于等于 600 dp 的设备，系统会选择 layout-sw600dp/main.xml（双面板）布局，否则系统就会选择 layout/main.xml（单面板）布局。