android - 设置onclicklistener时应用程序崩溃

Question

这是我的代码
帮帮我。如果我删除select.setonclicklistener。它的工作原理就像一个咒语，但是添加此行会使应用程序崩溃。甚至不显示此类。

public class Play extends Activity implements OnClickListener{
private Button sideshow;
private int i = 0; 
private ImageView[] user_images = new ImageView[6];
private int noc;
private int[] user_cards_ids = {R.id.card_1,R.id.card_2,R.id.card_3,R.id.card_4,R.id.card_5,R.id.card_6};
private ArrayList<Integer> user_cards;
@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.play);
    //Define
    sideshow = (Button) findViewById(R.id.sideshow);
    Bundle extras = getIntent().getExtras();
    noc = extras.getInt("noc");
    //End
    sideshow.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            Toast.makeText(Play.this, "Sideshow!", Toast.LENGTH_LONG).show();
        }
    }); 
}
@Override
public void onClick(View v) {
    if(v.getId()==sideshow.getId())
        Toast.makeText(Play.this, "Sideshow", Toast.LENGTH_LONG).show();
}

LOGCAT

11-01 19:55:35.000: E/AndroidRuntime(16587): in writeCrashedAppName, pkgName     :com.example.flash_teenpatti
11-01 19:55:35.000: E/AndroidRuntime(16587): FATAL EXCEPTION: main
11-01 19:55:35.000: E/AndroidRuntime(16587): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.flash_teenpatti/com.example.flash_teenpatti.Play}: java.lang.NullPointerException
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.os.Looper.loop(Looper.java:130)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.ActivityThread.main(ActivityThread.java:3683)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at java.lang.reflect.Method.invokeNative(Native Method)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at java.lang.reflect.Method.invoke(Method.java:507)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:880)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:638)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at dalvik.system.NativeStart.main(Native Method)
11-01 19:55:35.000: E/AndroidRuntime(16587): Caused by: java.lang.NullPointerException
11-01 19:55:35.000: E/AndroidRuntime(16587):    at com.example.flash_teenpatti.Play.onCreate(Play.java:34)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
11-01 19:55:35.000: E/AndroidRuntime(16587):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
11-01 19:55:35.000: E/AndroidRuntime(16587):    ... 11 more
11-01 19:55:35.050: E/ActivityManager(14462): Exception in bstSendTopActivityInfo while sending HttpPost: Connection to h t t p://10 . 0 . 2 . 2:2861 refused
11-01 19:55:35.980: E/ActivityManager(14462): Exception in bstSendTopActivityInfo while sending HttpPost: Connection to h t t p://10 . 0 . 2 . 2 :2861 refused
11-01 19:55:36.010: E/BstCommandProcessor-Application(14907): Exception in sendHttpRequest: Connection to h t t p://10.0.2.2:2861 refused

Answer 1

我猜这是一个空指针异常。确保您的按钮在R.layout.play布局中具有ID边秀。