按下按鈕播放不同的.mp3，具體取決於微調器選擇

Question

package com.RaffDev.RaffApp;

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

public class RaffAppActivity extends Activity implements 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

mp是 null 第一次運行此代碼並從微調器中選擇一些東西。 在pressPlay中添加 null 檢查，或在onCreate()中創建 mp 實例。