对于我正在创建的应用程序,它不允许我指定如何处理按钮,而是给我错误。该应用程序有助于在三首音乐歌曲之间切换。
代码挂了
package com.example.atvan.babysleeper;
import android.media.MediaPlayer;
import android.os.Handler;
import android.os.Message;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.TextView;
import com.example.atvan.babysleep.R;
public class MainActivity extends AppCompatActivity {
Button playBtn;
Button one;
Button two;
Button three;
SeekBar positionBar;
SeekBar volumeBar;
TextView elapsedTimeLabel;
TextView remainingTimelabel;
MediaPlayer mp;
int totalTime;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
playBtn = (Button) findViewById(R.id.playBtn);
elapsedTimeLabel = (TextView) findViewById(R.id.elapsedTimeLabel);
remainingTimelabel = (TextView) findViewById(R.id.remainingTimeLabel);
one = (Button) findViewById(R.id.one);
two = (Button) findViewById(R.id.two);
three = (Button) findViewById(R.id.three);
//Media player
public void setOne(View view){
mp = MediaPlayer.create(this, R.raw.music3);
}
public void setTwo(View view){
mp = MediaPlayer.create(this, R.raw.music2);
}
public void setThree(View view){
mp = MediaPlayer.create(this, R.raw.music1);
}
mp.setLooping(true);
mp.seekTo(0);
mp.setVolume(0.5f,0.5f);
totalTime = mp.getDuration();
//position Bar
positionBar = (SeekBar) findViewById(R.id.positionBar);
positionBar.setMax(totalTime);
positionBar.setOnSeekBarChangeListener(
new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
if (fromUser) {
mp.seekTo(progress);
positionBar.setProgress(progress);
}
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
}
);
//Volume Bar
volumeBar = (SeekBar) findViewById(R.id.volumeBar);
volumeBar.setOnSeekBarChangeListener(
new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
float volumeNum = progress/100f;
mp.setVolume(volumeNum, volumeNum);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
}
);
//thread (update positionBar amd timeLabel)
new Thread(new Runnable() {
@Override
public void run() {
while (mp != null) {
try{
Message msg = new Message();
msg.what = mp.getCurrentPosition();
handler.sendMessage(msg);
Thread.sleep(1000);
}catch (InterruptedException e){}
}
}
}).start();
}
private Handler handler;
{
handler = new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message msg) {
int currentPosition = msg.what;
// Update positionBar.
positionBar.setProgress(currentPosition);
// Update Labels.
String elapsedTime = createTimeLabel(currentPosition);
elapsedTimeLabel.setText(elapsedTime);
String remainingTime = "- " + createTimeLabel(totalTime - currentPosition);
remainingTimelabel.setText(remainingTime);
return true;
}
});
}
public String createTimeLabel(int time) {
String timeLabel = "";
int min = time / 1000 / 60;
int sec = time /1000 % 60;
timeLabel = min + ":";
if (sec<10) timeLabel += "0";
timeLabel += sec;
return timeLabel;
}
public void playBtnClick(View view) {
if (!mp.isPlaying()){
//stopping
mp.start();
playBtn.setBackgroundResource(R.drawable.stop);
} else {
//playing
mp.pause();
playBtn.setBackgroundResource(R.drawable.play);
}
}
它给出的错误是我的媒体播放器部分有一个非法的表达开始。它也表示给予;那里的某个地方。当放在代码末尾时。它没有给出任何错误,但应用程序没有运行
错误在这里
这里几乎没有逻辑错误。首先,您不能在另一个方法中编写方法,因此删除以下代码行onCreate()
并将其写入外部:
public void setOne(View view){ mp = MediaPlayer.create(this, R.raw.music3); }
public void setTwo(View view){ mp = MediaPlayer.create(this, R.raw.music2); }
public void setThree(View view){ mp = MediaPlayer.create(this, R.raw.music1); }
第二件事是你正在初始化你的mediaPlayer
内部这些方法,所以你应该做的是最初调用setOne()
方法,onCreate()
并在当前播放的歌曲结束后调用其他方法。
请仔细阅读本教程,虽然它显示了“在服务中构建媒体播放器”,但您可以在您的活动中执行此操作,并且对您来说,“第三步 – 构建媒体播放器”很重要。
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我来说两句