AndroidManifest.xml中:<?xml version="1.0" encoding="utf-8"?>
package="com.yang.lifecyle"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.yang.lifecyle.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.yang.lifecyle.OtherActivity"
android:label="name">
</activity>
</application>
MainActivity.java
package com.yang.lifecyle;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
private Button button;
private ButtonListener buttonListener;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonListener=new ButtonListener();
button=(Button)findViewById(R.id.button);
button.setOnClickListener(buttonListener);
}
class ButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent=new Intent();
intent.setClass(MainActivity.this, OtherActivity.class);
intent.putExtra("com.yang.lifecyle.Age", 20);
startActivity(intent);
}
}
fragment_main
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.yang.lifecyle.MainActivity$PlaceholderFragment" >
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="start" />
**
OtherActivity.java**
package com.yang.lifecyle;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.TextView;
public class OtherActivity extends ActionBarActivity{
private TextView textView;
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.other_activity);
Intent intent=getIntent();
int age=intent.getIntExtra("com.yang.lifecyle.Age",10);
textView=(TextView)findViewById(R.id.textView);
textView.setText("age "+age);
}
}
other_activity.xml
<?xml version="1.0" encoding="utf-8"?>
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="第二个Activity"
/>
LogCat
08-07 13:32:52.033: W/dalvikvm(391): threadid=1: thread exiting with uncaught exception (group=0x40015560)
08-07 13:32:52.133: E/AndroidRuntime(391): FATAL EXCEPTION: main
08-07 13:32:52.133: E/AndroidRuntime(391): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.yang.lifecyle/com.yang.lifecyle.MainActivity}: java.lang.NullPointerException
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1622)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.os.Handler.dispatchMessage(Handler.java:99)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.os.Looper.loop(Looper.java:123)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.ActivityThread.main(ActivityThread.java:3647)
08-07 13:32:52.133: E/AndroidRuntime(391): at java.lang.reflect.Method.invokeNative(Native Method)
08-07 13:32:52.133: E/AndroidRuntime(391): at java.lang.reflect.Method.invoke(Method.java:507)
08-07 13:32:52.133: E/AndroidRuntime(391): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-07 13:32:52.133: E/AndroidRuntime(391): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-07 13:32:52.133: E/AndroidRuntime(391): at dalvik.system.NativeStart.main(Native Method)
08-07 13:32:52.133: E/AndroidRuntime(391): Caused by: java.lang.NullPointerException
08-07 13:32:52.133: E/AndroidRuntime(391): at com.yang.lifecyle.MainActivity.onCreate(MainActivity.java:20)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-07 13:32:52.133: E/AndroidRuntime(391): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1586)
08-07 13:32:52.133: E/AndroidRuntime(391): ... 11 more
08-07 13:32:52.153: W/ActivityManager(61): Force finishing activity com.yang.lifecyle/.MainActivity
08-07 13:32:52.659: W/ActivityManager(61): Activity pause timeout for HistoryRecord{406fee18 com.yang.lifecyle/.MainActivity}
08-07 13:33:03.612: W/ActivityManager(61): Activity destroy timeout for HistoryRecord{406fee18 com.yang.lifecyle/.MainActivity}
08-07 13:33:05.007: W/ActivityManager(61): Activity idle timeout for HistoryRecord{408b0e00 com.yang.lifecyle/.MainActivity}