Question

我在Android编程中尝试自己。尝试编写一个由3个图像按钮组成的程序，如果首先单击，音乐播放，显示某个消息，如果第二个按下，则另一个音乐将与另一个消息显示一起播放。但错误信息显示＆＃34;复制局部变量mp2＆＃34;在为第二个medialplayer写的编码的第二行。请指导我。

package com.example.imagebutton;


import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
import android.widget.Toast;


public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        try{


            final MediaPlayer mp1;
            final MediaPlayer mp2 = null;


       ImageButton ib1 = (ImageButton) findViewById(R.id.imageButton1);
       mp1 = MediaPlayer.create(this, R.raw.muzikone);

        ib1.setOnClickListener (new View.OnClickListener()  {

            private MediaPlayer mp3;

            @Override
            public void onClick(View v) {

                Toast.makeText(MainActivity.this, "First Button Pressed!", Toast.LENGTH_LONG).show();
                if(mp2.isPlaying()){
                    mp2.reset();
                }else{
                    mp3.reset();
                }
                 mp1.start();


            }    



        });


        ImageButton ib2 = (ImageButton) findViewById(R.id.imageButton2);
        final MediaPlayer mp2 = MediaPlayer.create(this, R.raw.muziktwo);

         ib2.setOnClickListener (new View.OnClickListener()  {

            @Override
            public void onClick(View v) {

                Toast.makeText(MainActivity.this, "Second Button Pressed!", Toast.LENGTH_LONG).show();
                if(mp1.isPlaying()){
                    mp1.reset();
                }

                 mp2.start();


            }    



        });




         ImageButton ib3 = (ImageButton) findViewById(R.id.imageButton3);
         final MediaPlayer mp3 = MediaPlayer.create(this, R.raw.muzikthree);

          ib3.setOnClickListener (new View.OnClickListener()  {

            @Override
            public void onClick(View v) {

                Toast.makeText(MainActivity.this, "Third Button Pressed!", Toast.LENGTH_LONG).show();
                if(mp1.isPlaying()){
                    mp1.reset();
                }else{
                    mp2.reset();
                }

                 mp3.start();


            }    



        });


    }catch(Exception e) {

    }
    }
}

Answer 1

mp2被声明两次，如下所示：

final MediaPlayer mp2 = null;

在这里

final MediaPlayer mp2 = MediaPlayer.create(this, R.raw.muziktwo);

要解决此问题，请删除其中一个声明。

注意：我认为您的代码中存在严重的范围问题，例如阅读this lesson可能有帮助

重复的局部变量mp2

1 个答案: