java - 单击按钮时应用程序崩溃

Question

每当我单击按钮时，我的应用程序就会崩溃。我做错了什么？

public void onClick(View v) {

            int primaryLength = PRIMARY.length;
            final String primaryText = PRIMARY[rnd.nextInt(primaryLength)];
            int secondaryLength = SECONDARY.length;
            final String secondaryText = SECONDARY[rnd.nextInt(secondaryLength)];
            final TextView textOne = (TextView)findViewById(R.id.textView1);
            final TextView textTwo = (TextView)findViewById(R.id.textView2);
            textOne.setText(primaryText);
            textTwo.setText(secondaryText);

            String primeT = primaryText;
            Uri media = Uri.parse(primeT);
            mpButtonOne = MediaPlayer.create(MainActivity.this, media);
            mpButtonOne.start();
            mpButtonOne.setOnCompletionListener(new OnCompletionListener() {
                public void onCompletion(MediaPlayer mpButtonOne) {
                    String primeS = secondaryText;
                    Uri media2 = Uri.parse(primeS);
                    mpButtonTwo = MediaPlayer.create(MainActivity.this, media2);
                    mpButtonTwo.start();
                    mpButtonTwo.setOnCompletionListener(new soundListener1());
                    {
                    }
                }

我希望将 TextView 中显示的随机选择的文本输入为媒体播放器声音文件的位置，这些单词是我的原始文件夹中声音文件的名称。我有点新，真的不确定这是否是正确的方法。

09-11 16:50:40.128: E/AndroidRuntime(12531): FATAL EXCEPTION: main
09-11 16:50:40.128: E/AndroidRuntime(12531): java.lang.NullPointerException
09-11 16:50:40.128: E/AndroidRuntime(12531):    at com.spunktrunk.nastylittleman.MainActivity$1.onClick(MainActivity.java:62)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at android.view.View.performClick(View.java:2408)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at android.view.View$PerformClick.run(View.java:8816)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at android.os.Handler.handleCallback(Handler.java:587)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at android.os.Handler.dispatchMessage(Handler.java:92)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at android.os.Looper.loop(Looper.java:123)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at android.app.ActivityThread.main(ActivityThread.java:4669)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at java.lang.reflect.Method.invokeNative(Native Method)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at java.lang.reflect.Method.invoke(Method.java:521)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
09-11 16:50:40.128: E/AndroidRuntime(12531):    at dalvik.system.NativeStart.main(Native Method)
09-11 16:50:40.128: W/ActivityManager(237):   Force finishing activity com.spunktrunk.nastylittleman/.MainActivity

Answer 1

根据您的网址，调用 Media.create 可能会返回空值 ( look at the documentation here )。如果是这样，您的代码正在尝试调用 null 上的方法，这会导致您的 NPE(空指针异常)

您当然可以像这样更改代码:

 mpButtonOne = MediaPlayer.create(MainActivity.this, media);
 if (mButtonOne==null){
        //display a Toast message here
        return;
 }
 mpButtonOne.start();