使用androidStudio中的MediaPlayer播放列表中的随机歌曲? [英] Playing random songs from a list using MediaPlayer in androidStudio?

问题描述

所以，这是东西.我遵循《新波士顿教程》为活动添加背景音乐.但是后来我想，如果我可以添加歌曲列表，然后使用随机数在后台播放列表中的歌曲，那会不是很好.现在，它可以工作了，但事情是这样，在我按了两次播放按钮后，它给了我这个错误消息(下面的图像以红色显示)，并且我无法理解该错误消息的含义.谁能建议我如何解决错误?

So, here is the thing. I was following the New Boston Tutorials for adding background music to an activity. But then i was thinking wouldn't it be nice if i can add a list of songs and then use the Random number to play songs from the list in the background. Now, it works but here is the thing, after i press the play button twice it gives me this error message(image attached below in red) and i am unable to understand what the error message means. Can anyone suggest me how i can fix the error?

package com.example.user.testapp5;

import android.app.Activity;
import android.graphics.Color;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.util.Random;

import static com.example.user.testapp5.R.raw.u;

public class MainActivity extends Activity {

    Button b1,b2;
    TextView t1;

    MediaPlayer [] s = new MediaPlayer[2];
    int n;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        s[0] = MediaPlayer.create(MainActivity.this,R.raw.u);
        s[1] = MediaPlayer.create(MainActivity.this,R.raw.k);

        b1 = (Button)findViewById(R.id.display);//start button to play the song
        b2 = (Button)findViewById(R.id.Sbutton);//stop button to stop the song

        t1 = (TextView)findViewById(R.id.Tdisplay);

        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                t1.setText("Hey Welcome");
                t1.setTextColor(Color.BLUE);
                t1.setTextSize(10);

                for(int i =0 ;i<1;i++)
                {
                    Random r = new Random();
                    n = r.nextInt(2);

                    s[n].start();



                }
            }
        });


        b2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                s[n].stop();

            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

推荐答案

这是因为媒体播放器尚未准备好播放您的歌曲.在为Media Player实例设置数据源之后，您应该立即调用 player.prepareAsync(); ，当准备好Media Player之后，将执行 onPrepared 方法.方法，开始播放:

This is because media player is not ready to play your song yet. After setting data source for the Media Player instance, you should call player.prepareAsync(); now when the Media Player is prepared, the onPrepared method will be executed.Inside this method, start the playback:

@Override
public void onPrepared(MediaPlayer mp) {
//start playback
mp.start();
}

完成任务后，您应该释放所有资源，例如:

And after completion of your task you should release all resources like :

 player.stop();
 player.release();

为避免同一首媒体播放器实例同时播放多首歌曲，我建议创建单例类，该类一次仅返回一个实例.如果您使用服务来播放背景歌曲，我建议您遵循本教程:-

For avoiding multiple songs play simultaneously with same media player instance I would suggest to create singleton class which returns only one instance at a time. If you are using service for background song playing, I would suggest to follow this tutorial :- http://code.tutsplus.com/tutorials/create-a-music-player-on-android-song-playback--mobile-22778
Hope this will help you !!!

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