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  • Android应用开发基础篇(1)Button

    一、概述

           Button,顾名思义就是按钮的意思,它主要的功能是响应用户按下按钮时的动作。

    二、应用

         新建一个工程,名字为MyButton,在/res/layout/main.xml文件中添加以下内容:

    1 <Button
    2 android:id="@+id/button"
    3 android:layout_width="fill_parent"
    4 android:layout_height="wrap_content"
    5 android:text="Click"
    6 />

    添加后main.xml文件的内容为:

     1 <?xml version="1.0" encoding="utf-8"?>
    2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    3 android:layout_width="fill_parent"
    4 android:layout_height="fill_parent"
    5 android:orientation="vertical" >
    6
    7 <TextView
    8 android:layout_width="fill_parent"
    9 android:layout_height="wrap_content"
    10 android:text="@string/hello" />
    11
    12 <Button
    13 android:id="@+id/button"
    14 android:layout_width="fill_parent"
    15 android:layout_height="wrap_content"
    16 android:text="Click"
    17 />
    18
    19 </LinearLayout>

    接着修改MyButtonActivity.java文件,在MyButtonActivity类里声明一个Button对象mButton

    private Button mButton = null;

    在onCreate()函数里通过findViewById()函数实例化mButton

    mButton = (Button)findViewById(R.id.button);

    紧接着编写mButton的监听函数

    mButton.setOnClickListener(new View.OnClickListener()
    {

    @Override
    public void onClick(View v)
    {
    // TODO Auto-generated method stub
    PlayToast("You Clicked Button");
    }
    });

    其中PlayToast()函数是通过Toast类用来显示"You Clicked Button"这串字符串的,比较简单,如下所示:

    private void PlayToast(String s)
    {
    Toast toast = Toast.makeText(this, s , Toast.LENGTH_LONG);
    toast.show();
    }

    好了。下面是MyButtonActivity.java文件的完整内容:

     1 package com.nan.button;
    2
    3 import android.app.Activity;
    4 import android.os.Bundle;
    5 import android.view.View;
    6 import android.widget.Button;
    7 import android.widget.Toast;
    8
    9
    10
    11 public class MyButtonActivity extends Activity
    12 {
    13 private Button mButton = null;
    14
    15
    16 /** Called when the activity is first created. */
    17 @Override
    18 public void onCreate(Bundle savedInstanceState)
    19 {
    20 super.onCreate(savedInstanceState);
    21 setContentView(R.layout.main);
    22
    23 mButton = (Button)findViewById(R.id.button);
    24 mButton.setOnClickListener(new View.OnClickListener()
    25 {
    26
    27 @Override
    28 public void onClick(View v)
    29 {
    30 // TODO Auto-generated method stub
    31 PlayToast("You Clicked Button");
    32 }
    33 });
    34
    35 }
    36
    37
    38 private void PlayToast(String s)
    39 {
    40 Toast toast = Toast.makeText(this, s , Toast.LENGTH_LONG);
    41 toast.show();
    42 }
    43
    44 }

    运行程序,并点击按钮,效果如下:

     



     

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  • 原文地址:https://www.cnblogs.com/lknlfy/p/2351740.html
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