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package com.example.activity;
import android.os.Bundle;
import android.view.*;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.support.v4.app.NavUtils;
@SuppressLint("ParserError")
public class MainActivity extends Activity {
public Button myButton=null;
public TextView myTextView=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myButton=(Button)findViewById(R.id.myButton);
myButton.setText("jump to activytyOther");
myButton.setOnClickListener(new myButtonMonitor());
myTextView=(TextView)findViewById(R.id.myTextView);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
public class myButtonMonitor implements View.OnClickListener{
public void onClick(View v) {
Intent intent=new Intent();
intent.setClass(MainActivity.this, OtherActivity.class);
intent.putExtra("msg", 123);
MainActivity.this.startActivity(intent);
MainActivity.this.myTextView.setText("button clicked!");//这里没有问题
}
}
}
package com.example.activity;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class OtherActivity extends Activity{
public TextView myTextView=null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.myTextView=(TextView)findViewById(R.id.a);//这里是我感觉不对的地方
this.myTextView.setText("This Is Other Activty!");
}
}
<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" >
<TextView
android:id="@+id/myTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:padding="@dimen/padding_medium"
android:text="@string/hello_world"
tools:context=".MainActivity" />
<Button
android:id="@+id/myButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</RelativeLayout>
<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" >
<TextView
android:id="@+id/a"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:padding="@dimen/padding_medium"
android:text="@string/hello_world"
tools:context=".OtherActivity" />
</RelativeLayout>
public class a extends Activity{
private Button jump=null;
private TextView tv_a=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.a);
jump=(Button)findViewById(R.id.jump);
jump.setOnClickListener((OnClickListener) new Monitor());
tv_a=(TextView)findViewById(R.id.a);
tv_a.setText("A");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.layout.a, menu);
return true;
}
private class Monitor implements OnClickListener{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent=new Intent();
intent.setClass(a.this, b.class);
a.this.startActivity(intent);
}
}
}
public class b extends Activity {
private TextView tv_b=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.b);
tv_b = (TextView)findViewById(R.id.b);
tv_b.setText("B");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.layout.b, menu);
return true;
}
}
<?xml version="1.0" encoding="utf-8"?>
<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" >
<TextView
android:id="@+id/a"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:padding="10dp"
android:text="@string/hello_a"
tools:context=".a" />
<Button
android:id="@+id/jump"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<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" >
<TextView
android:id="@+id/b"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:padding="10dp"
android:text="@string/hello_b"
tools:context=".b" />
</RelativeLayout>
<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" >
<TextView
android:id="@+id/a"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:padding="@dimen/padding_medium"
android:text="@string/hello_world"
tools:context=".a" />
<Button
android:id="@+id/jump"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</RelativeLayout>
<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" >
<TextView
android:id="@+id/b"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:padding="@dimen/padding_medium"
android:text="@string/hello_world"
tools:context=".b" />
</RelativeLayout>
//a.java
package com.example.p;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.support.v4.app.NavUtils;
public class a extends Activity {
private Button jump=null;
private TextView tv_a=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_a);
jump=(Button)findViewById(R.id.jump);
jump.setOnClickListener(new Monitor());
tv_a=(TextView)findViewById(R.id.a);
tv_a.setText("A");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_a, menu);
return true;
}
private class Monitor implements View.OnClickListener{
public void onClick(View v) {
Intent intent=new Intent();
intent.setClass(a.this, b.class);
a.this.startActivity(intent);
}
}
}
//b.java
package com.example.p;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.support.v4.app.NavUtils;
public class b extends Activity {
private TextView tv_b=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_b);
tv_b.setText("B");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_b, menu);
return true;
}
}
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.p"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".a"
android:label="@string/title_activity_a" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".b"
android:label="@string/title_activity_b" >
</activity>
</application>
</manifest>
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_other);
View v=findViewById(R.id.a);
System.out.println(v);
tv=(TextView)v;
// tv.setText("This Is Other Activty!");//调试到这句话出问题