我在我的模拟器上收到这些错误，应用程序崩溃了。
logcat的
08-30 22:18:20.066: E/AndroidRuntime(860): FATAL EXCEPTION: main
08-30 22:18:20.066: E/AndroidRuntime(860): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mojoo/com.example.mojoo.main}: java.lang.NullPointerException
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.os.Handler.dispatchMessage(Handler.java:99)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.os.Looper.loop(Looper.java:123)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.ActivityThread.main(ActivityThread.java:3683)
08-30 22:18:20.066: E/AndroidRuntime(860): at java.lang.reflect.Method.invokeNative(Native Method)
08-30 22:18:20.066: E/AndroidRuntime(860): at java.lang.reflect.Method.invoke(Method.java:507)
08-30 22:18:20.066: E/AndroidRuntime(860): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-30 22:18:20.066: E/AndroidRuntime(860): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-30 22:18:20.066: E/AndroidRuntime(860): at dalvik.system.NativeStart.main(Native Method)
08-30 22:18:20.066: E/AndroidRuntime(860): Caused by: java.lang.NullPointerException
08-30 22:18:20.066: E/AndroidRuntime(860): at com.example.mojoo.main.onCreate(main.java:26)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-30 22:18:20.066: E/AndroidRuntime(860): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
08-30 22:18:20.066: E/AndroidRuntime(860): ... 11 more
08-30 22:18:21.965: I/Process(860): Sending signal. PID: 860 SIG: 9
08-30 22:19:08.275: D/AndroidRuntime(894): Shutting down VM
08-30 22:19:08.275: W/dalvikvm(894): threadid=1: thread exiting with uncaught exception (group=0x40015560)
08-30 22:19:08.285: E/AndroidRuntime(894): FATAL EXCEPTION: main
08-30 22:19:08.285: E/AndroidRuntime(894): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mojoo/com.example.mojoo.main}: java.lang.NullPointerException
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.os.Handler.dispatchMessage(Handler.java:99)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.os.Looper.loop(Looper.java:123)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.ActivityThread.main(ActivityThread.java:3683)
08-30 22:19:08.285: E/AndroidRuntime(894): at java.lang.reflect.Method.invokeNative(Native Method)
08-30 22:19:08.285: E/AndroidRuntime(894): at java.lang.reflect.Method.invoke(Method.java:507)
08-30 22:19:08.285: E/AndroidRuntime(894): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-30 22:19:08.285: E/AndroidRuntime(894): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-30 22:19:08.285: E/AndroidRuntime(894): at dalvik.system.NativeStart.main(Native Method)
08-30 22:19:08.285: E/AndroidRuntime(894): Caused by: java.lang.NullPointerException
08-30 22:19:08.285: E/AndroidRuntime(894): at com.example.mojoo.main.onCreate(main.java:26)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-30 22:19:08.285: E/AndroidRuntime(894): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
08-30 22:19:08.285: E/AndroidRuntime(894): ... 11 more
这是我的src main.java
package com.example.mojoo;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
public class main extends Activity {
ImageView iv;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv=(ImageView) findViewById(R.id.imageView1);
Button b = (Button) findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(intent, 0);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Bitmap bm = (Bitmap) data.getExtras().get("data");
iv.setImageBitmap(bm);
}
}
编辑对于问题的一些参考，我正在添加xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1.03"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="307dp"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="172dp"
android:layout_height="match_parent"
android:orientation="vertical" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="fill_parent" >
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:text="MOJO ULTIMATE"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView2"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/textView2"
android:src="@drawable/mojohdpi" />
</RelativeLayout>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageButton
android:id="@+id/imageButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="14dp"
android:src="@drawable/camerahdpi" />
<ImageButton
android:id="@+id/imageButton2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/imageButton1"
android:layout_below="@+id/imageButton1"
android:src="@drawable/adohdpi" />
<ImageButton
android:id="@+id/imageButton3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/imageButton2"
android:layout_centerHorizontal="true"
android:src="@drawable/vediohdpi" />
<ImageButton
android:id="@+id/imageButton4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/imageButton3"
android:layout_centerHorizontal="true"
android:src="@drawable/livehdpi" />
<ImageButton
android:id="@+id/imageButton5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignRight="@+id/imageButton4"
android:layout_below="@+id/imageButton4"
android:src="@drawable/browsehdpi" />
</RelativeLayout>
</LinearLayout>
</LinearLayout>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<EditText
android:id="@+id/editText1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="18dp"
android:ems="10"
android:hint="Write an annotation..."
android:inputType="textMultiLine" />
<RadioButton
android:id="@+id/radioButton2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_marginRight="114dp" />
<RadioButton
android:id="@+id/radioButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_toLeftOf="@+id/radioButton2" />
<ImageButton
android:id="@+id/imageButton6"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_above="@+id/radioButton2"
android:layout_alignParentRight="true"
android:layout_below="@+id/editText1"
android:src="@drawable/okhdpi" />
</RelativeLayout>
</LinearLayout>
</LinearLayout>
</LinearLayout>
答案 0 :(得分：5)
看来你的b是空的。确保以下语句中的按钮ID正确。
Button b = (Button) findViewById(R.id.button1);