有人能给出一个简单的例子，每秒钟更新一个文本框左右?
我想要制作一个飞行的球，并需要每秒计算/更新球的坐标，这就是为什么我需要某种计时器。
我从这里什么也得不到。
当前回答
对于那些不能依赖Chronometer的人，我从其中一个建议中创建了一个实用程序类:
public class TimerTextHelper implements Runnable {
private final Handler handler = new Handler();
private final TextView textView;
private volatile long startTime;
private volatile long elapsedTime;
public TimerTextHelper(TextView textView) {
this.textView = textView;
}
@Override
public void run() {
long millis = System.currentTimeMillis() - startTime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
textView.setText(String.format("%d:%02d", minutes, seconds));
if (elapsedTime == -1) {
handler.postDelayed(this, 500);
}
}
public void start() {
this.startTime = System.currentTimeMillis();
this.elapsedTime = -1;
handler.post(this);
}
public void stop() {
this.elapsedTime = System.currentTimeMillis() - startTime;
handler.removeCallbacks(this);
}
public long getElapsedTime() {
return elapsedTime;
}
}
要使用..，只需这样做:
TimerTextHelper timerTextHelper = new TimerTextHelper(textView);
timerTextHelper.start();
…
timerTextHelper.stop();
long elapsedTime = timerTextHelper.getElapsedTime();
其他回答
如果你已经有了时间。
public class Timer {
private float lastFrameChanged;
private float frameDuration;
private Runnable r;
public Timer(float frameDuration, Runnable r) {
this.frameDuration = frameDuration;
this.lastFrameChanged = 0;
this.r = r;
}
public void update(float dt) {
lastFrameChanged += dt;
if (lastFrameChanged > frameDuration) {
lastFrameChanged = 0;
r.run();
}
}
}
这很简单! 你创建了一个新的定时器。
Timer timer = new Timer();
然后扩展计时器任务
class UpdateBallTask extends TimerTask {
Ball myBall;
public void run() {
//calculate the new position of myBall
}
}
然后以一定的更新间隔将新任务添加到Timer中
final int FPS = 40;
TimerTask updateBall = new UpdateBallTask();
timer.scheduleAtFixedRate(updateBall, 0, 1000/FPS);
声明:这不是理想的解决方案。这是使用定时器类的解决方案(由OP要求)。在Android SDK中，建议使用Handler类(在接受的答案中有示例)。
enter code here
Thread th=new Thread(new Runnable() {
@Override
public void run() {
try { for(int i=0;i<5;i++) {
b1.setText(""+i);
Thread.sleep(5000);
runOnUiThread(new Runnable() {
@Override
public void run() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
pp();
}
}
});
}} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
th.start();
这里是解决方案，您需要在代码中添加以下类。您可以直接向XML文件添加视图。
import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;
import java.util.Locale;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;
public class TimerTextView extends TextView {
private static final int DEFAULT_INTERVAL = 1000;
private Timer timer = new Timer();
private long endTime = 0;
private long interval = DEFAULT_INTERVAL;
private boolean isCanceled = false;
public TimerTextView(Context context) {
super(context);
}
public TimerTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public TimerTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public TimerTextView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
stopTimer();
}
@Override protected void onVisibilityChanged(View changedView, int visibility) {
super.onVisibilityChanged(changedView, visibility);
if (VISIBLE == visibility) {
startTimer();
} else {
stopTimer();
}
}
public void setInterval(long interval) {
if (interval >= 0) {
this.interval = interval;
stopTimer();
startTimer();
}
}
public void setEndTime(long endTime) {
if (endTime >= 0) {
this.endTime = endTime;
stopTimer();
startTimer();
}
}
private void startTimer() {
if (endTime == 0) {
return;
}
if (isCanceled) {
timer = new Timer();
isCanceled = false;
}
timer.scheduleAtFixedRate(new TimerTask() {
@Override public void run() {
if (null == getHandler()) {
return;
}
getHandler().post(new Runnable() {
@Override public void run() {
setText(getDurationBreakdown(endTime - System.currentTimeMillis()));
}
});
}
}, 0, interval);
}
private void stopTimer() {
timer.cancel();
isCanceled = true;
}
private String getDurationBreakdown(long diff) {
long millis = diff;
if (millis < 0) {
return "00:00:00";
}
long hours = TimeUnit.MILLISECONDS.toHours(millis);
millis -= TimeUnit.HOURS.toMillis(hours);
long minutes = TimeUnit.MILLISECONDS.toMinutes(millis);
millis -= TimeUnit.MINUTES.toMillis(minutes);
long seconds = TimeUnit.MILLISECONDS.toSeconds(millis);
return String.format(Locale.ENGLISH, "%02d:%02d:%02d", hours, minutes, seconds);
//return "${getWithLeadZero(hours)}:${getWithLeadZero(minutes)}:${getWithLeadZero(seconds)}"
}
}
对于那些不能依赖Chronometer的人，我从其中一个建议中创建了一个实用程序类:
public class TimerTextHelper implements Runnable {
private final Handler handler = new Handler();
private final TextView textView;
private volatile long startTime;
private volatile long elapsedTime;
public TimerTextHelper(TextView textView) {
this.textView = textView;
}
@Override
public void run() {
long millis = System.currentTimeMillis() - startTime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
textView.setText(String.format("%d:%02d", minutes, seconds));
if (elapsedTime == -1) {
handler.postDelayed(this, 500);
}
}
public void start() {
this.startTime = System.currentTimeMillis();
this.elapsedTime = -1;
handler.post(this);
}
public void stop() {
this.elapsedTime = System.currentTimeMillis() - startTime;
handler.removeCallbacks(this);
}
public long getElapsedTime() {
return elapsedTime;
}
}
要使用..，只需这样做:
TimerTextHelper timerTextHelper = new TimerTextHelper(textView);
timerTextHelper.start();
…
timerTextHelper.stop();
long elapsedTime = timerTextHelper.getElapsedTime();
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