Question

当我尝试多次单击按钮时，我遇到了此错误。以下是logcat中的错误：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.huiiy.myapplication, PID: 3933
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.start()' on a null object reference
        at com.example.huiiy.myapplication.Activity9$13.onClick(Activity9.java:288)
        at android.view.View.performClick(View.java:5712)
        at android.view.View$PerformClick.run(View.java:22514)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6141)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

下面是我的应用程序的编码：

    iv_33.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            MediaPlayer ivbsound = new MediaPlayer();
            ivbsound = MediaPlayer.create(Activity9.this,R.raw.ivbutton);
            //          MediaPlayer ivbsound = MediaPlayer.create(Activity9.this,R.raw.ivbutton);
            ivbsound.start();
            int theCard = Integer.parseInt((String) view.getTag());
            doStuff(iv_33, theCard);
        }
    });

Answer 1

您好，尝试用其他音频文件创建播放器。也许ivbutton文件已损坏

[更新]

如果您要重用它，请声明此声音播放器的惰性属性，并在每次单击播放时将其

class MyActivity extends AppCompatActivity {
    private MediaPlayer soundPlayer = null;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        soundPlayer = MediaPlayer.create(this, R.raw.ivbutton);

        iv_33.setOnClickListener(view -> {
            soundPlayer.start();
            int theCard = Integer.parseInt((String) view.getTag());
            doStuff(iv_33, theCard);
        });
    }
}

Answer 2

这意味着创建MediaPlayer失败（也许您有关于它的警告/调试消息）。创建新的MediaPlayer然后用新的MediaPlayer代替它是没有用的。

检查R.raw.ivbutton是否存在并与良好的媒体相对应（可以运行）。

个人而言，这就是我的工作方式：


    File mediaFile = obj.getFile();
    MediaPlayer mediaPlayer = new MediaPlayer();
    try {
        mediaFile.setReadable(true); // be sure that the program have access to the media content
        
        // this try/catch is to support multiple Android version
        try {
             mediaPlayer.setDataSource(mediaFile.getAbsolutePath());
        } catch (Exception e) {
             mediaPlayer.setDataSource(context, Uri.fromFile(mediaFile));
        }
    
        mediaPlayer.prepare(); // prepare it, after you can change volume ...
    } catch (Exception e){
        e.printStackTrace();
    }
    mediaPlayer.start(); // finally start the media

Answer 3

请确保您尝试播放的声音文件格式受here中的一项检查清单支持。因为在不支持文件的情况下MediaPlayer.create返回null，这会导致空指针异常。另外我建议在调用ivbsound.start（）之前检查if（ivbsound！= null）;

java.lang.NullPointerException：尝试在空对象引用上

3 个答案: