Question

这是我的代码帮帮我们。如果我删除select.setonclicklistener。它就像一个魅力，但添加此行会使应用程序崩溃。甚至没有展示这个课程。

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的

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。确保你的R.layout.play布局中有一个具有id sideshow的Button。

Answer 2

您已在类定义中实现了OnClickListener并在线定义。我建议你使用已实现的类。

public class Play extends Activity implements OnClickListener{

所以你只需将onclicklistener设置为 this 并取出内联处理程序。

    sideshow.setOnClickListener(this);
}

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

实现的好处是其他类可以看到实现的内容并实际使用这些函数。例如，在片段类中，如果实现了方法，则可以轻松调用活动类中的方法。

    Activity activity = this.getActivity();
    if (OnClickListener.class.isInstance(activity)) {
    OnClickListener adl = (OnClickListener) activity;
            adl.onClick(myView);
    }

Answer 3

你确定你没有在layout.xml中设置类似android:onclick="method"的内容吗？如果是，可能存在冲突。

当我设置onclicklistener时应用程序崩溃

3 个答案: