Android学习笔记-Activity的生命周期
界面activity_main.xml
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<RelativeLayout 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"
tools:context="com.example.activity_05.MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<Button
android:id="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_marginTop="22dp"
android:text="启动第二个Activity" />
</RelativeLayout>
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界面second.xml
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="This is the second activity" />
</LinearLayout>
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MainActivity.java
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package com.example.activity_05;
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.view.View.OnClickListener;
public class MainActivity extends ActionBarActivity {
private Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
System.out.println("MainActivity onCreate：第一次调用Activity的时候执行");
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setClass(MainActivity.this, SecondActivity.class);
MainActivity.this.startActivity(intent);
}
});
}
@Override
protected void onResume() {
System.out.println("MainActivity onResume");
super.onResume();
}
//以上三个方法执行完毕之后这个Activity就可以使用了
@Override
protected void onStart() {
System.out.println("MainActivity onStart：Activity处于可见状态的时候调用");
super.onStart();
}
@Override
protected void onRestart() {
System.out.println("MainActivity onRestart：Activity又可以得到用户焦点的时候调用");
System.out.println("当从第二个Activity又回到第一个Activity时调用此方法");
System.out.println("然后调用onResume方法就可以显示出来");
System.out.println("然后调用第二个Activity的onStop、onDestroy。第二个Activity就被销毁掉了");
super.onRestart();
}
@Override
protected void onPause() {
System.out.println("MainActivity onPause");
System.out.println("如果在执行当前Activity的时候又启动了一个Activity就会调用当前Activity的此方法");
System.out.println("然后依次调用新启动的Activity的onCreate、onStart、onResume");
System.out.println("然后调用第一个Activity的onStop方法");
super.onPause();
}
@Override
protected void onStop() {
System.out.println("MainActivity onStop");
//如果第二个Activity把第一个Activity完全遮挡住就调用这个函数
super.onStop();
}
@Override
protected void onDestroy() {
System.out.println("MainActivity onDestroy");
super.onDestroy();
}
} |
SecondActivity.java
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package com.example.activity_05;
import android.app.Activity;
import android.os.Bundle;
public class SecondActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
}
@Override
protected void onStart() {
System.out.println("SecondActivity onStart");
super.onStart();
}
@Override
protected void onRestart() {
System.out.println("SecondActivity onRestart");
super.onRestart();
}
@Override
protected void onResume() {
System.out.println("SecondActivity onResume");
super.onResume();
}
@Override
protected void onPause() {
System.out.println("SecondActivity onPause");
super.onPause();
}
@Override
protected void onStop() {
System.out.println("SecondActivity onStop");
super.onStop();
}
@Override
protected void onDestroy() {
System.out.println("SecondActivity onDestroy");
super.onDestroy();
}
} |
AndroidManifest.xml
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<activity android:name=".SecondActivity" android:label="第二个Activity"/>
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日志输出如下
每次显示栈顶Activity的内容
