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  • 调用另一个Activity

    参考自Google官方文档Traning/Getting Started/Building a simple user interface, Startinganother activity,http://developer.android.com/training/basics/firstapp/building-ui.html

    1、创建主Activity

    使用Eclipse新建项目MyFirstApp,UI布局如下:

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:orientation="horizontal"
        tools:context=".MainActivity">
     
        <EditText
            android:id="@+id/et_message"
            android:layout_height="wrap_content"
           android:layout_width="0dp"
            android:layout_weight="1"
            android:hint="@string/input_here"/>
       
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/click"
            android:onClick="sendMessage"/>
     
    </LinearLayout>


    注意通过权重来分配尺寸的方式

    组件1:

    android:layout_width="0dp"
    android:layout_weight="1"

    组件2:

    android:layout_width="wrap_content"

    2、在主类中指定onclick所对应的sendMessage方法

    package com.lujinhong.androidtraningmyfirstapp;
     
    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.view.Menu;
    import android.view.View;
    import android.widget.EditText;
     
    public class MainActivity extends Activity{
       
         public final static String EXTRA_MESSAGE="com.lujinhong.myfirstapp.MESSAGE";
     
        @Override
        protected void onCreate(Bundle savedInstanceState){
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
        }
     
        @Override
        public boolean onCreateOptionsMenu(Menu menu){
            // Inflate themenu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.main, menu);
            return true;
        }
       
        public void sendMessage(View v){
                       
            EditText et_message=(EditText)this.findViewById(R.id.et_message);
            String message= et_message.getText().toString().trim();
           
            Intent intent= new Intent(this,DisplayMessageActivity.class);
            intent.putExtra(EXTRA_MESSAGE, message);
           
            this.startActivity(intent);
           
        }
     
    }


    (1)关于intent

    An Intent isan object that provides runtime binding between separate components (such astwo activities). TheIntent representsan app’s "intent to do something." You can use intents for a widevariety of tasks, but most often they’re used to startanother activity.

    (2)调用另一个activity的步骤:

    l  首先取得editText中的文字

    EditText et_message = (EditText) this.findViewById(R.id.et_message);
    String message = et_message.getText().toString().trim();

    l  然后创建一下intent,并把文字作为K-V形式保存到intent中

            Intent intent= new Intent(this,DisplayMessageActivity.class);
            intent.putExtra(EXTRA_MESSAGE, message);

    创建intent时,通过一个类名,指定调用哪个类文件。

    l  最后启动一个新的activity.

    this.startActivity(intent);
    

    3、显示另一个Activity

    package com.lujinhong.androidtraningmyfirstapp;
     
    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.view.Menu;
    import android.widget.TextView;
     
    public class DisplayMessageActivityextends Activity{
     
        @Override
        protected void onCreate(Bundle savedInstanceState){
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_display_message);
           
            // Get the messagefrom the intent
            Intent intent= getIntent();
            String message= intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
     
            // Create the textview
            TextView textView=new TextView(this);
            textView.setTextSize(40);
            textView.setText(message);
     
            // Set the textview as the activity layout
            setContentView(textView);
           
        }
     
        @Override
        public boolean onCreateOptionsMenu(Menu menu){
            // Inflate themenu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.display_message, menu);
            return true;
        }
     
    }


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  • 原文地址:https://www.cnblogs.com/jediael/p/4304203.html
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