Question

我是android新手。当我运行我的应用程序时，它在横向模式下运行良好，但在纵向模式下，应用程序强制关闭，在日志中显示以下内容

05-31 16:48:30.958: W/KeyCharacterMap(428): No keyboard for id 0
05-31 16:48:30.958: W/KeyCharacterMap(428): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
05-31 16:50:45.728: D/AndroidRuntime(484): Shutting down VM
05-31 16:50:45.728: W/dalvikvm(484): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
05-31 16:50:45.758: E/AndroidRuntime(484): FATAL EXCEPTION: main
05-31 16:50:45.758: E/AndroidRuntime(484): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kalmas/com.kalmas.Kalma2}: java.lang.NullPointerException
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.os.Looper.loop(Looper.java:123)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.app.ActivityThread.main(ActivityThread.java:4627)
05-31 16:50:45.758: E/AndroidRuntime(484):  at java.lang.reflect.Method.invokeNative(Native Method)
05-31 16:50:45.758: E/AndroidRuntime(484):  at java.lang.reflect.Method.invoke(Method.java:521)
05-31 16:50:45.758: E/AndroidRuntime(484):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-31 16:50:45.758: E/AndroidRuntime(484):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-31 16:50:45.758: E/AndroidRuntime(484):  at dalvik.system.NativeStart.main(Native Method)
05-31 16:50:45.758: E/AndroidRuntime(484): Caused by: java.lang.NullPointerException
05-31 16:50:45.758: E/AndroidRuntime(484):  at com.kalmas.Kalma2.onCreate(Kalma2.java:52)
05-31 16:50:45.758: E/AndroidRuntime(484):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-31 16:50:45.758: E/AndroidRuntime(484):  at          android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
05-31 16:50:45.758: E/AndroidRuntime(484):  ... 11 more
05-31 16:50:48.108: I/Process(484): Sending signal. PID: 484 SIG: 9

我的Kalma2.java的代码是

package com.kalmas;

import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;

public class Kalma2 extends Activity {

    public void onCreate(Bundle savedInstanceState) {
        final MediaPlayer   kalma2  =   MediaPlayer.create(this,   R.raw.kalma2);
        super.onCreate(savedInstanceState);
    setContentView(R.layout.kalma2);

    ImageView prev2 =   (ImageView)findViewById(R.id.prev2);

    prev2.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            kalma2.stop();
            startActivity(new Intent(Kalma2.this,Kalma1.class));
        }
    });

    ImageView   next2   =   (ImageView)findViewById(R.id.next2);
    next2.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            kalma2.stop();
            startActivity(new Intent(Kalma2.this,Kalma3.class));
        }
    });

    ImageView pause =   (ImageView)findViewById(R.id.pause2);
    pause.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            kalma2.pause();
        }
    });

    ImageView play  =   (ImageView)findViewById(R.id.play2);
    play.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            kalma2.start();
        }
    });

    ImageView kalma =   (ImageView)findViewById(R.id.kalma2);

    kalma.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            kalma2.start();
        }
    });



}

}

Answer 1

据我所知，在第52行，你试图将一个点击监听器附加到ImageView。

ImageView play  =   (ImageView)findViewById(R.id.play2);
play.setOnClickListener(new OnClickListener() { ...

您确定您的布局包含ID为play2的ImageView吗？很高兴获得kalma2.xml的代码：）

Answer 2

如果没有看到你的布局并确切知道第52行是什么，很难说，但最可能的问题是你的findViewById个调用之一返回null，当你使用它来尝试设置clickListener你得到了NPE。

检查ID并确保您匹配大小写以及ID。

Android应用程序在纵向模式下强制关闭，但在横向上运行良好

2 个答案: