java - 按下按钮可根据微调器选择播放不同的 .mp3

Question

包 com.RaffDev.RaffApp;

导入 android.app.Activity;导入 android.media.MediaPlayer;导入 android.os.Bundle;导入 android.view.View;导入 android.widget.Toast;导入 android.widget.AdapterView;导入 android.widget.ArrayAdapter;导入 android.widget.Spinner;

公共(public)类 RaffAppActivity 扩展 Activity 实现 View.OnClickListener,``AdapterView.OnItemSelectedListener{

/*Regular Variables*/
String copyright = "Raff App \n\nVersion: Alpha 0.0.1\n\n(c) Copyright Raff App contributors and others 2011. All rights reserverd";
public int soundSelection;
MediaPlayer mp;

/*Called at the beginning of the application*/
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Spinner spinner = (Spinner) findViewById(R.id.spinner1);
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.soundEntries, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);        
}

/*Button Functions*/
public void onClick(View v){}

public void infoClick(View v){

    Toast.makeText(this, copyright, Toast.LENGTH_LONG).show();
}

public void pressPlay(View v){
    switch(soundSelection){
    case 1: 
        if(mp.isPlaying())
        mp.reset();
        mp = MediaPlayer.create(getApplicationContext(), R.raw.pleaseprettyface);
        mp.start();
        break;
    case 2: 
        if(mp.isPlaying())
        mp.reset();
        mp = MediaPlayer.create(getApplicationContext(),R.raw.sheeesh);
        mp.start();
        break;
    case 3: 
        if(mp.isPlaying())
        mp.reset();
        mp = MediaPlayer.create(getApplicationContext(),R.raw.heaintdodat);
        mp.start();
        break;
    case 4: 
        if(mp.isPlaying())
        mp.reset();
        mp = MediaPlayer.create(getApplicationContext(),R.raw.thedousky);
        mp.start();
        break;
    case 5: 
        if(mp.isPlaying())
        mp.reset();
        mp = MediaPlayer.create(getApplicationContext(),R.raw.nmouth);
        mp.start();
        break;


    }

}



/*Spinner Functions*/
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
    soundSelection = (Integer) parent.getItemAtPosition(pos);
}

public void onNothingSelected(AdapterView<?> parent) {
      // Do nothing.
}

}

Answer 1

第一次运行此代码并从微调器中选择某些内容时，

mp 为 null。在 pressPlay 中添加空检查，或者在 onCreate() 中创建 mp 实例。