我试图获取播放嵌入视频时暂停所花费的时间。当我在视频再次开始播放时添加计算（如下所示）时，我收到错误。错误日志似乎表明我的按钮是问题，但它在下面添加代码行之前工作正常。提前致谢
主：
public class ThirdActivity extends Activity {
myVideoView v;
private static final String TAG = "MEDIA";
private TextView tv;
MediaPlayer.OnCompletionListener videoListener = new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
Log.d("onCompletion", "Total time paused: " + v.getTotalTimeMillis());
double totalPause = v.getTotalTimeMillis();
double percent = 23000/(totalPause+23000);
int pauseNumber = v.pauseCount();
//long[] pauseTimes = v.pauseDuration();
File root = android.os.Environment.getExternalStorageDirectory();
File dir = new File (root.getAbsolutePath() + "/download");
dir.mkdirs();
Date e = new Date();
CharSequence s = DateFormat.format("MM-dd-yy HH-mm-ss", e.getTime());
File file = new File(dir, s.toString() + "videoStats1.txt");
String p = "Percent="+String.valueOf(percent)+"\n\nNumber of Pauses="+String.valueOf(pauseNumber);
String[] r = null;
/**
if (pauseNumber > 0) {
for (int t=0; t<=pauseNumber; t++){
r[t] = "Pause"+String.valueOf(pauseNumber+1)+" duration="+String.valueOf(pauseTimes[t])+"\n\n";
}
}
**/
try {
FileOutputStream f = new FileOutputStream(file);
PrintWriter pw = new PrintWriter(f);
pw.println(p);
/**
for (int t=0; t<=pauseNumber; t++){
pw.println(r[t]);
}
**/
pw.flush();
pw.close();
} catch (FileNotFoundException f) {
f.printStackTrace();
Log.i(TAG, "***** File not found. Did you" + " add a permission to the manifest?");
}
Intent intent = new Intent(ThirdActivity.this, FourthActivity.class);
startActivity(intent);
}
};
public void PlayPause(View view) {
//Do something in response to button press
if(v.isPlaying()){
v.pause();
} else {
v.start();
}
}
我的视频观看课程：
public class myVideoView extends VideoView{
long lastPausedTime = 0; // The time of the last pause (milliseconds)
long totalPausedTime = 0; // The total time paused (milliseconds)
int numberOfPauses = 0; // Number of Pauses
long[] thisPause = null; // Array of individual Pause durations
public myVideoView(Context context) {
super(context);
}
public myVideoView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public myVideoView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public void pause() {
lastPausedTime = System.currentTimeMillis();
super.pause();
}
@Override
public void start() {
if (lastPausedTime != 0) {
long startTime = System.currentTimeMillis();
totalPausedTime += startTime - lastPausedTime;
thisPause[numberOfPauses] = startTime - lastPausedTime; //makes app fail
numberOfPauses++;
}
super.start();
}
public long getTotalTimeMillis() {
return totalPausedTime;
}
public int pauseCount() {
return numberOfPauses;
}
错误日志：
07-01 11:24:05.521: E/AndroidRuntime(25972): FATAL EXCEPTION: main
07-01 11:24:05.521: E/AndroidRuntime(25972): Process: com.example.motorimagery, PID: 25972
07-01 11:24:05.521: E/AndroidRuntime(25972): java.lang.IllegalStateException: Could not execute method of the activity
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.view.View$1.onClick(View.java:3823)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.view.View.performClick(View.java:4438)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.view.View$PerformClick.run(View.java:18422)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.os.Handler.handleCallback(Handler.java:733)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.os.Handler.dispatchMessage(Handler.java:95)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.os.Looper.loop(Looper.java:136)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.app.ActivityThread.main(ActivityThread.java:5017)
07-01 11:24:05.521: E/AndroidRuntime(25972): at java.lang.reflect.Method.invokeNative(Native Method)
07-01 11:24:05.521: E/AndroidRuntime(25972): at java.lang.reflect.Method.invoke(Method.java:515)
07-01 11:24:05.521: E/AndroidRuntime(25972): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-01 11:24:05.521: E/AndroidRuntime(25972): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-01 11:24:05.521: E/AndroidRuntime(25972): at dalvik.system.NativeStart.main(Native Method)
07-01 11:24:05.521: E/AndroidRuntime(25972): Caused by: java.lang.reflect.InvocationTargetException
07-01 11:24:05.521: E/AndroidRuntime(25972): at java.lang.reflect.Method.invokeNative(Native Method)
07-01 11:24:05.521: E/AndroidRuntime(25972): at java.lang.reflect.Method.invoke(Method.java:515)
07-01 11:24:05.521: E/AndroidRuntime(25972): at android.view.View$1.onClick(View.java:3818)
07-01 11:24:05.521: E/AndroidRuntime(25972): ... 11 more
07-01 11:24:05.521: E/AndroidRuntime(25972): Caused by: java.lang.NullPointerException
07-01 11:24:05.521: E/AndroidRuntime(25972): at com.example.motorimagery.myVideoView.start(myVideoView.java:37)
07-01 11:24:05.521: E/AndroidRuntime(25972): at com.example.motorimagery.ThirdActivity.PlayPause(ThirdActivity.java:92)
答案 0 :(得分：0)
那是因为将thisPause定义为null但从不给它一个新值，因此在行中
**thisPause[numberOfPauses] = startTime - lastPausedTime;
您的应用程序抛出NullPointerException您必须为thisPause
编辑：
再看看之后，我认为只保存最后一个暂停值就足够了。或者你有什么理由需要所有这些吗？
或者您可以使用List来保存暂停，因为数组必须具有预定的大小，不得更改。
List<Long> thisPause = new ArrayList<Long>();
public void pause() {
lastPausedTime = System.currentTimeMillis();
thisPause.add(lastPausedTime); //Add the last paused time to the end of the List
super.pause();
}
public void start() {
if (lastPausedTime != 0) {
long startTime = System.currentTimeMillis();
totalPausedTime += startTime - lastPausedTime;
//Option 1 Begin:
thisPause.set(numberOfPauses,startTime - lastPausedTime);
//This should work, assuming you never change number of pauses anywhere else
numberOfPauses++;
//Option 1 End
//Option 2 Begin:
thisPause.add(startTime-lastPausedTime);
//option 2 End
}
//...
}
如果使用第二个选项，要检索最后一个值，请使用
thisPause.get(thisPause.size()-1);
我希望这对你有用