当我启动应用程序时，MainActivity成功启动，但是当我在文本编辑字段中插入文本时，我按下按钮应用程序崩溃
Android清单文件
<uses-sdk
android:minSdkVersion="10"
android:targetSdkVersion="10" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.sateesh.explicit_intents.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.sateesh.explicit_intents.Second"
android:label="@string/app_name">
</activity>
</application>
</manifest>
这是Main_Activity：
package com.sateesh.explicit_intents;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Refernce of UI objects
final EditText et=(EditText)findViewById(R.id.editText1);
Button b =(Button) findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i= new Intent(MainActivity.this, Second.class);
// Getting
i.putExtra("thetext", et.getText().toString());
startActivity(i);
}
});
}
@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;
}
}
main_activity.xml：
<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=".MainActivity" >
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:ems="10" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/editText1"
android:layout_below="@+id/editText1"
android:text="Go To Second Activity" />
</RelativeLayout>
第二项活动：
package com.sateesh.explicit_intents;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
public class Second extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView tv=(TextView)findViewById(R.id.textView1);
tv.setText(getIntent().getExtras().getString("thetext"));
}
}
second.xml：
<?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="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
</LinearLayout>
当我尝试在模拟器上运行它时。 MainActivity成功启动。但是，当我插入文本并按下按钮程序崩溃，我得到以下错误。
10-28 00:43:16.692: D/gralloc_goldfish(2002): Emulator without GPU emulation detected.
10-28 00:43:17.462: W/KeyCharacterMap(2002): No keyboard for id 0
10-28 00:43:17.462: W/KeyCharacterMap(2002): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
10-28 00:43:18.393: D/AndroidRuntime(2002): Shutting down VM
10-28 00:43:18.393: W/dalvikvm(2002): threadid=1: thread exiting with uncaught exception (group=0xb6f794f0)
10-28 00:43:18.433: E/AndroidRuntime(2002): FATAL EXCEPTION: main
10-28 00:43:18.433: E/AndroidRuntime(2002): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sateesh.explicit_intents/com.sateesh.explicit_intents.Second}: java.lang.NullPointerException
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.os.Handler.dispatchMessage(Handler.java:99)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.os.Looper.loop(Looper.java:130)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.ActivityThread.main(ActivityThread.java:3683)
10-28 00:43:18.433: E/AndroidRuntime(2002): at java.lang.reflect.Method.invokeNative(Native Method)
10-28 00:43:18.433: E/AndroidRuntime(2002): at java.lang.reflect.Method.invoke(Method.java:507)
10-28 00:43:18.433: E/AndroidRuntime(2002): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-28 00:43:18.433: E/AndroidRuntime(2002): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-28 00:43:18.433: E/AndroidRuntime(2002): at dalvik.system.NativeStart.main(Native Method)
10-28 00:43:18.433: E/AndroidRuntime(2002): Caused by: java.lang.NullPointerException
10-28 00:43:18.433: E/AndroidRuntime(2002): at com.sateesh.explicit_intents.Second.onCreate(Second.java:14)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-28 00:43:18.433: E/AndroidRuntime(2002): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
10-28 00:43:18.433: E/AndroidRuntime(2002): ... 11 more
10-28 00:43:20.711: I/Process(2002): Sending signal. PID: 2002 SIG: 9
当我启动应用程序时，MainActivity成功启动，但是当我在文本编辑字段中插入文本时，我按下按钮应用程序崩溃
答案 0 :(得分：1)
更改此行：
setContentView(R.layout.activity_main);
在您的Second活动中：
setContentView(R.layout.second);
TextView布局中没有activity_main.xml且ID为textView1。但是在second.xml布局中有。由于您的活动名为Second，因此我在这里做一个疯狂的猜测并说，您为Second活动设置了错误的布局。