在MediaPlayer中添加崩潰我的應用程序 - 無法輸出聲音

Question

我目前正在編寫一個Android應用程序，這是我做的第一個。所以我是新的android工作室。在這裏和在線查看其他帖子。我試圖從它輸出聲音。我已經在MediaPlayer中添加並將我的聲音文件放入/ res/raw中，但是當我嘗試運行我的應用程序時，它已經崩潰。

package com.example.myfirstapp; 

import android.media.MediaPlayer; 
import android.os.Bundle; 
import android.os.Handler; 
import android.support.v7.app.ActionBarActivity; 
import android.view.MotionEvent; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 

import net.objecthunter.exp4j.Expression; 
import net.objecthunter.exp4j.ExpressionBuilder; 

import static com.example.myfirstapp.R.id.fourfivesix; 
import static com.example.myfirstapp.R.id.operators; 

//import net.objecthunter.exp4j.Expression; 
//import net.objecthunter.exp4j.ExpressionBuilder; 

public class MainActivity extends ActionBarActivity { 
    private int[] operatorButtons = {operators}; 
    private int[] numericButtons = {R.id.onetwothree, fourfivesix, R.id.seveneightninezero}; 
    private boolean lastNumeric, stateError; 
    private TextView txtScreen; 
    private static final int TAP_TIMEOUT = 400; 
    MediaPlayer one = MediaPlayer.create(this, R.raw.one); 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     // Find the TextView 
     this.txtScreen = (TextView) findViewById(R.id.txtScreen); 
     // Find and set OnClickListener to numeric buttons 
//  setNumericOnClickListener(); 
     // Find and set OnClickListener to operator buttons, equal button and decimal point button 
//  setOperatorOnClickListener(); 

     Button onetwothree = (Button) findViewById(R.id.onetwothree); 
     onetwothree.setOnTouchListener(new View.OnTouchListener() { 

      Handler handler = new Handler(); 

      int numberOfTaps = 0; 
      long lastTapTimeMs = 0; 
      long touchDownMs = 0; 

      @Override 
      public boolean onTouch(View v, MotionEvent event) { 
       switch (event.getAction()) { 
        case MotionEvent.ACTION_DOWN: 
         touchDownMs = System.currentTimeMillis(); 
         break; 
        case MotionEvent.ACTION_UP: 
         handler.removeCallbacksAndMessages(null); 
         if ((System.currentTimeMillis() - touchDownMs) > 1000) { 
          //it was not a tap 

          numberOfTaps = 0; 
          lastTapTimeMs = 0; 
          break; 
         } 

         if (numberOfTaps > 0 
           && (System.currentTimeMillis() - lastTapTimeMs) < 1000) { 
          numberOfTaps += 1; 
         } else { 
          numberOfTaps = 1; 
         } 
         lastTapTimeMs = System.currentTimeMillis(); 

         if (numberOfTaps == 1) { 
          handler.postDelayed(new Runnable() { 

           @Override 
           public void run() { 
            if (txtScreen.getText().toString() == "") { 
             txtScreen.setText("1"); 
             one.start(); 
            } else txtScreen.append("1"); 
           } 
          }, 1000); 



         }else if (numberOfTaps == 2) { 
          handler.postDelayed(new Runnable() { 
           @Override 
           public void run() { 
            if (txtScreen.getText().toString() == "") { 
             txtScreen.setText("2"); 
            } else txtScreen.append("2"); 
           } 
          }, 1000); 

         } else if (numberOfTaps == 3) { 
          if (txtScreen.getText().toString() == "") { 
           txtScreen.setText("3"); 
          } else txtScreen.append("3"); 
         } 
       } 

       return false; 
      } 
     }); 

以上是我的代碼的相關部分。我在頂部創建了一個名爲「one」的媒體播放器，然後在需要使用one.start()時試圖調用它，還有什麼我需要添加到我的代碼中才能使用？

在添加MediaPlayer代碼之前，我的應用程序運行良好。

Answer 1

試試這個：

呼叫MediaPlayer.create()裏面的onCreate（）

public class MainActivity extends ActionBarActivity { 

MediaPlayer one; 

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     one = MediaPlayer.create(this, R.raw.one); 

這裏是一個很好example