1、创建主Activity
使用Eclipse新建项目MyFirstApp,UI布局如下：
[html]
<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：
[html]
android:layout_width="0dp"
android:layout_weight="1"
组件2：
[html]
android:layout_width="wrap_content"
2、在主类中指定onclick所对应的sendMessage方法
[java]
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
[java]
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
[java]
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.
[java]
this.startActivity(intent);
3、显示另一个Activity
[java]
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.
