单击按钮时应用崩溃

Question

Whenever I click my button my app crashes. What am I doing wrong?

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());
                    {
                    }
                }

I want the randomly selected text that is displayed in textviews to be entered as the location for the mediaplayer sound files, the words are the names of the sound files in my raw folder. I'm a bit new and really not sure if this is the right way to go about it.

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

Depending on your url, calling Media.create might have returned a null value ( look at the documentation here ). If so, your code is trying to call a method on null, which causes your NPE (Null Pointer Exception)

You could of course change your code like this:

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