android编程2.4
活动生命周期其实就是程序执行的各种过程，程序刚执行的时候叫oncreate，结束叫ondestroy。在这些函数里由我们来写代码初始化或者释放变量空间。以下为示意图：首先在菜单里点close project把原来的项目关闭，我们再新建一个empty activity的项目，然后把activity_main.xml修改为：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.xinwei.lifecycle.MainActivity">
<Button
android:id="@+id/button_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="button1" />
<Button
android:id="@+id/button_2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="button2" />
</LinearLayout>
然后在mainactivity.java旁边新建两个activity文件，一个叫NormalActivity.java,一个叫DialogActivity.java两个empty activity，把两个layout文件分别命名为normal_layout和dialog_layout，然后把androidmanifest.xml文件修改为以下代码<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.xinwei.lifecycle">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".NormalActivity" />
<activity
android:name=".DialogActivity"
android:theme="@style/Theme.AppCompat.Dialog" />
</application>
</manifest>
然后把mainactivity.java文件修改为：package com.example.xinwei.lifecycle;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private static String TAG="MainActivity";
private MyListener myListener;
private Intent intent1;
private Intent intent2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG,"onCreate");
setContentView(R.layout.activity_main);
Button btn1 = (Button)findViewById(R.id.button_1);
Button btn2 = (Button)findViewById(R.id.button_2);
intent1 = new Intent(this,NormalActivity.class);
intent2 = new Intent(this,DialogActivity.class);
myListener = new MyListener();
btn1.setOnClickListener(myListener);
btn2.setOnClickListener(myListener);
}
protected class MyListener implements View.OnClickListener{
@Override
public void onClick(View view) {
switch(view.getId()){
case R.id.button_1:
startActivity(intent1);
break;
case R.id.button_2:
startActivity(intent2);
}
}
}
@Override
protected void onStart() {
super.onStart();
Log.d(TAG,"onStart");
}
@Override
protected void onResume() {
super.onResume();
Log.d(TAG,"onResume");
}
@Override
protected void onPause() {
super.onPause();
Log.d(TAG,"onPause");
}
@Override
protected void onStop() {
super.onStop();
Log.d(TAG,"onStop");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(TAG,"onDestroy");
}
@Override
protected void onRestart() {
super.onRestart();
Log.d(TAG,"onRestart");
}
}然后开启程序在logcat下输入框输入MainActivity就可以看到我们写的日志，这需要你自己实验我这里就不说了，如图：
效果图：
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