【从头学android】在两个Activity之间实现界面切换

1.java

/**
 * 
 */
package com.itest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

/**
 * @author Robin
 */
public class ITestP3Activity extends Activity {
	Button b1;
	View v1;

	/** Called when the activity is first created. */
	@Override
	public void onCreate( Bundle savedInstanceState )
	{
		super.onCreate( savedInstanceState );
		//缓存View1
		v1 = getLayoutInflater().inflate( R.layout.p31, null );
		//动态修改v1中内容
		b1 = (Button) v1.findViewById( R.id.button1 );
		b1.setOnClickListener( new OnClickListener() {
			@Override
			public void onClick( View v )
			{
				Intent in = new Intent();
				in.setClassName( getApplicationContext(), "com.itest.ITestP4Activity" );
				startActivity( in );
			}
		} );
		//切换到v1
		setContentView( v1 );
	}
	
}

2.java

/**
 * 
 */
package com.itest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

/**
 * @author Robin
 */
public class ITestP4Activity extends Activity {
	Button b1;
	View v1;

	/** Called when the activity is first created. */
	@Override
	public void onCreate( Bundle savedInstanceState )
	{
		super.onCreate( savedInstanceState );
		//缓存View1
		v1 = getLayoutInflater().inflate( R.layout.p41, null );
		//动态修改v1中内容
		b1 = (Button) v1.findViewById( R.id.button1 );
		b1.setOnClickListener( new OnClickListener() {
			@Override
			public void onClick( View v )
			{
				Intent in = new Intent();
				in.setClassName( getApplicationContext(), "com.itest.ITestP3Activity" );
				startActivity( in );
			}
		} );
		//切换到v1
		setContentView( v1 );
	}
	
}

切换两个Activity使用了Intent类,其实常用这个类的会有调用拨打电话、发短信等外部程序

要注意的是每次的切换，都是新启动的Activity程序，可以通过下面的代码测试一下

/**
 * 
 */
package com.itest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

/**
 * @author Robin
 */
public class ITestP3Activity extends Activity {
	Button b1;
	Button b2;
	View v1;
	TextView tv1;

	/** Called when the activity is first created. */
	@Override
	public void onCreate( Bundle savedInstanceState )
	{
		super.onCreate( savedInstanceState );
		//缓存View1
		v1 = getLayoutInflater().inflate( R.layout.p31, null );
		//动态修改v1中内容
		b1 = (Button) v1.findViewById( R.id.button1 );
		b1.setOnClickListener( new OnClickListener() {
			@Override
			public void onClick( View v )
			{
				Intent in = new Intent();
				in.setClassName( getApplicationContext(), "com.itest.ITestP4Activity" );
				startActivity( in );
			}
		} );

		tv1 = (TextView) v1.findViewById( R.id.textView1 );
		
		b2 = (Button) v1.findViewById( R.id.button2 );
		b2.setOnClickListener( new OnClickListener() {
			@Override
			public void onClick( View v )
			{
				tv1.setText( System.currentTimeMillis()+"" );
				// TODO Auto-generated method stub
			}
		});
		//切换到v1
		setContentView( v1 );
	}
	
}

会发现在切换之前TextView上显示的数字，在切换回来之后消失了

然后按系统的返回键，会一页一页的返回上一页（可以返回到有数字的一页），从而说明每次的切换，都是新启动的Activity程序