android - 尝试在按钮单击时播放声音时出现空指针异常

Question

我正在尝试开发一个在单击按钮时播放不同鼓声的应用程序。使用我当前的代码，当我尝试单击按钮时，我得到了一个空指针异常。

这是我的代码：

package com.example.pocketbeatbox;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;

public class MainActivity extends Activity {
MediaPlayer kick;
MediaPlayer snare;
MediaPlayer clap;
MediaPlayer openHat;
MediaPlayer closedHat;

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

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}
public void playKick(View view) {
      kick.start();
      kick.release();
   };
}