Activity基础小结

Activity：与用户交互的基本呈现单元

 

3种状态：运行、停止(Home键)、暂停(长按Home键半透明，后面遮住前面)

 

生命周期：7个方法

 

基本操作：

 

1.启动一个Activity

 

由MainActivity通过按钮跳到Aty1，按钮监听器代码如下：

			Intent i = new Intent(MainActivity.this,Aty1.class); 
			startActivity(i);

 

2.关闭一个Activity

 

在Aty1点击按钮关闭，按钮监听器代码如下：

finish();

 

3.传递数据

 

从MainActivity把数据传到Aty1，两种处理方式：

 

(1)：简单数据：

 

MainActivity.java核心代码：

	Intent i = new Intent(MainActivity.this,Aty1.class); 
	i.putExtra("txt1", "Hello!");
	startActivity(i);

 

Aty1.java核心代码：

tvOut.setText(getIntent().getStringExtra("txt1"));

 

(2)：复杂数据

 

MainActivity.java核心代码：

Intent i = new Intent(MainActivity.this,Aty1.class); 
Bundle data = new Bundle();
data.putString("Hello");
i.putExtras(data);
startActivity(i);

 

Aty.java核心代码：

Bundle data = getIntent().getExtras();
String txt1 = data.getString("txt1");
tvOut.setText(txt1);

 

4.取回第二个Activity返回的数据，不能用startActivity()，而应该用startActivityForResult()

 

MainActivity.java核心代码：

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	// TODO Auto-generated method stub
    	String result = data.getStringExtra("result");
    	tvOut = (TextView) findViewById(R.id.tvOut);
    	tvOut.setText(result);
        super.onActivityResult(requestCode, resultCode, data);
    }

 

Aty1.java核心代码：

btnClose.setOnClickListener(new View.OnClickListener() {
		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			Intent i = new Intent();
			i.putExtra("result", "Hi");
			setResult(0, i);
		    finish();	
		}
	});

 

现整体代码如下，目的：验证7个方法的执行顺序；采用传送复杂数据的方式从MainActivity把“Hello”传到Aty1，并且接收Aty1传回的“Hi”

 

MainActivity.java

package com.example.jk_jc_sidazujian;

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

public class MainActivity extends Activity {

	private Button btnStartAty1; 
	private TextView tvOut;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		btnStartAty1 = (Button) findViewById(R.id.btnStartAty1);
		btnStartAty1.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
			Intent i = new Intent(MainActivity.this,Aty1.class); 
//				i.putExtra("txt1", "Hello!");
//				startActivity(i);
		        Bundle data = new Bundle();
		        data.putString("txt1", "Hello");
			    i.putExtras(data);
				startActivityForResult(i, 0);
			}
		});
		System.out.println("onCreat");
		
	}
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	// TODO Auto-generated method stub
    	String result = data.getStringExtra("result");
    	tvOut = (TextView) findViewById(R.id.tvOut);
    	tvOut.setText(result);
    	
    	
    	super.onActivityResult(requestCode, resultCode, data);
    }
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}
    @Override
    protected void onStart() {
    	// TODO Auto-generated method stub
    	super.onStart();
    	System.out.println("onStart");
    }
    
    @Override
    protected void onResume() {
    	// TODO Auto-generated method stub
    	super.onResume();
    	System.out.println("onResume");
    }
    
    @Override
    protected void onPause() {
    	// TODO Auto-generated method stub
    	super.onPause();
    	System.out.println("onPause");
    }
    
    @Override
    protected void onStop() {
    	// TODO Auto-generated method stub
    	super.onStop();
    	System.out.println("onStop");
    }
    
    @Override
    protected void onDestroy() {
    	// TODO Auto-generated method stub
    	super.onDestroy();
    	System.out.println("onDestory");
    }
    
    @Override
    protected void onRestart() {
    	// TODO Auto-generated method stub
    	super.onRestart();
    	System.out.println("onRestart");
    }
}

 

Aty1.java

package com.example.jk_jc_sidazujian;

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

public class Aty1 extends Activity {
	
	private Button btnClose;
	private TextView tvOut;
@Override
protected void onCreate(Bundle savedInstanceState) {
	// TODO Auto-generated method stub
	super.onCreate(savedInstanceState);
	setContentView(R.layout.aty1);
	tvOut= (TextView) findViewById(R.id.tvOut);
	Bundle data = getIntent().getExtras();
	String txt1 = data.getString("txt1");
	tvOut.setText(txt1);
	
	btnClose = (Button) findViewById(R.id.btnClose);
	
	btnClose.setOnClickListener(new View.OnClickListener() {
		
		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			Intent i = new Intent();
			i.putExtra("result", "Hi");
			setResult(0, i);
		    finish();	
		}
	});
}
}

相应布局xml文件就不赘述了。

 

运行效果如下：

 

点击start Aty1按钮

 

点击btnclose