[英]Playing background music android error
這是我知道導致錯誤的代碼:
final MediaPlayer background = MediaPlayer.create(Start.this, R.raw.music);
background.setLooping(true); // Set looping
background.setVolume(100,100);
background.start();
final ImageButton mute = (ImageButton) findViewById(R.id.mute);
final boolean[] mute_off = {true};
mute.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
background.stop();
if (mute_off[0]) {
mute.setBackgroundResource(R.drawable.sound_off);
mute_off[0] = true;
} else {
mute.setBackgroundResource(R.drawable.sound_on);
mute_off[0] = false;
}
}
});
當我啟動應用程序時,它崩潰,錯誤是: “不幸的是,應用程序已停止工作”
由(來自logcat)引起:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
怎么了?
您的代碼很好,不包括您提供錯誤的ID或圖像不存在於drawable中。 這很好
setContentView(R.layout.activity_main);
final MediaPlayer background = MediaPlayer.create(this, R.raw.sun);
background.setLooping(true); // Set looping
background.setVolume(100,100);
background.start();
final ImageButton mute = (ImageButton) findViewById(R.id.edt1);
final boolean[] mute_off = {true};
mute.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
background.stop();
if (mute_off[0]) {
Log.v("value is======", "true");
// mute.setBackgroundResource(R.drawable.sound_off);
mute_off[0] = true;
} else {
Log.v("value is======", "false");
// mute.setBackgroundResource(R.drawable.sound_on);
mute_off[0] = false;
}
}
});
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