我有一个带有3个按钮的活动，可以开始相同的活动，但布局不同。按钮2＆amp; 3正在工作但按钮1正在给出运行时异常（应用程序崩溃）。这是源代码：
public class Choose extends Activity implements OnClickListener{
Button sniper;
Button machine;
Button colt;
int btnsound;
Intent t;
SoundPool spool;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.choose);
t = new Intent(Choose.this, MainActivity.class);
sniper=(Button)findViewById(R.id.button1);
machine=(Button)findViewById(R.id.button2);
colt=(Button)findViewById(R.id.button3);
colt.setOnClickListener(this);
sniper.setOnClickListener(this);
machine.setOnClickListener(this);
this.setVolumeControlStream(AudioManager.STREAM_MUSIC);
spool = new SoundPool(1, AudioManager.STREAM_MUSIC, 0);
btnsound= spool.load(this, R.raw.btn, 1);
}
public void btnsound(){
AudioManager audioManager = (AudioManager) getSystemService(AUDIO_SERVICE);
float volume = (float) audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
spool.play(btnsound, volume, volume, 1, 0, 1f);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId()) {
case R.id.button1:
t.putExtra("button", 1);
startActivity(t);
btnsound();
break;
case R.id.button2:
t.putExtra("button", 2);
startActivity(t);
btnsound();
break;
case R.id.button3:
t.putExtra("button", 3);
startActivity(t);
btnsound();
break;
}
}
}
布局代码：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/choosewall" >
<ScrollView
android:id="@+id/scrollView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:scrollbars="none" >
<TableLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
>
<TableRow
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="4dp"
android:layout_marginRight="4dp"
android:layout_marginTop="20dp"
android:layout_weight="1" >
<Button
android:id="@+id/button1"
android:layout_width="300sp"
android:layout_height="100sp"
android:layout_centerHorizontal="true"
android:background="@drawable/sniperstyle" />
</TableRow>
<TableRow
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="4dp"
android:layout_marginRight="4dp"
android:layout_marginTop="20dp"
android:layout_weight="1" >
<Button
android:id="@+id/button2"
android:layout_width="300sp"
android:layout_height="100sp"
android:layout_centerHorizontal="true"
android:background="@drawable/machinegunstyle" />
</TableRow>
<TableRow
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="4dp"
android:layout_marginRight="4dp"
android:layout_marginTop="20dp"
android:layout_weight="1" >
<Button
android:id="@+id/button3"
android:layout_width="300sp"
android:layout_height="100sp"
android:layout_centerHorizontal="true"
android:background="@drawable/pistolstyle" />
</TableRow>
</TableLayout>
</ScrollView>
</RelativeLayout>
单击button1时的堆栈跟踪：
07-15 00:30:56.202: E/AndroidRuntime(32404): FATAL EXCEPTION: main
07-15 00:30:56.202: E/AndroidRuntime(32404): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jouni.camsniper/com.jouni.camsniper.MainActivity}: java.lang.NullPointerException
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.os.Handler.dispatchMessage(Handler.java:99)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.os.Looper.loop(Looper.java:137)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.ActivityThread.main(ActivityThread.java:5041)
07-15 00:30:56.202: E/AndroidRuntime(32404): at java.lang.reflect.Method.invokeNative(Native Method)
07-15 00:30:56.202: E/AndroidRuntime(32404): at java.lang.reflect.Method.invoke(Method.java:511)
07-15 00:30:56.202: E/AndroidRuntime(32404): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-15 00:30:56.202: E/AndroidRuntime(32404): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-15 00:30:56.202: E/AndroidRuntime(32404): at dalvik.system.NativeStart.main(Native Method)
07-15 00:30:56.202: E/AndroidRuntime(32404): Caused by: java.lang.NullPointerException
07-15 00:30:56.202: E/AndroidRuntime(32404): at com.jouni.camsniper.MainActivity.onCreate(MainActivity.java:73)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.Activity.performCreate(Activity.java:5104)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
07-15 00:30:56.202: E/AndroidRuntime(32404): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
07-15 00:30:56.202: E/AndroidRuntime(32404): ... 11 more
07-15 00:30:58.664: I/Process(32404): Sending signal. PID: 32404 SIG: 9
答案 0 :(得分：1)
07-15 00:30:56.202: E/AndroidRuntime(32404): Caused by: java.lang.NullPointerException
07-15 00:30:56.202: E/AndroidRuntime(32404): at com.jouni.camsniper.MainActivity.onCreate(MainActivity.java:73)
相当明显。您正在调用一个引用方法，该方法在MainActivity.java中的第73行上没有任何内容。
答案 1 :(得分：1)
对于那些单击注册按钮时崩溃的人。我从register.java文件中删除了这段代码，现在它可以正常工作。
if（Build.VERSION.SDK_INT＆gt; = Build.VERSION_CODES.ICE_CREAM_SANDWICH）{ ActionBar actionBar = getActionBar（）; actionBar.hide（）;
}