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
他是更简单的解决方案，工作在我的应用程序。
public class MyActivity extends Acitivity {
TextView myTextView;
boolean someCondition=true;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_activity);
myTextView = (TextView) findViewById(R.id.refreshing_field);
//starting our task which update textview every 1000 ms
new RefreshTask().execute();
}
//class which updates our textview every second
class RefreshTask extends AsyncTask {
@Override
protected void onProgressUpdate(Object... values) {
super.onProgressUpdate(values);
String text = String.valueOf(System.currentTimeMillis());
myTextView.setText(text);
}
@Override
protected Object doInBackground(Object... params) {
while(someCondition) {
try {
//sleep for 1s in background...
Thread.sleep(1000);
//and update textview in ui thread
publishProgress();
} catch (InterruptedException e) {
e.printStackTrace();
};
return null;
}
}
}
其他回答
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();
void method(boolean u,int max)
{
uu=u;
maxi=max;
if (uu==true)
{
CountDownTimer uy = new CountDownTimer(maxi, 1000)
{
public void onFinish()
{
text.setText("Finish");
}
@Override
public void onTick(long l) {
String currentTimeString=DateFormat.getTimeInstance().format(new Date());
text.setText(currentTimeString);
}
}.start();
}
else{text.setText("Stop ");
}
import kotlin.concurrent.fixedRateTimer
val timer = fixedRateTimer("Tag", false, 1000, 2500) { /* Your code here */ }
Kotlin非常简单
因为这个问题仍然从谷歌搜索吸引了很多用户(关于Android定时器)，我想插入我的两个硬币。
首先，Timer类在Java 9中将被弃用(请阅读已接受的答案)。
官方建议的方法是使用ScheduledThreadPoolExecutor，它更有效，功能丰富，可以额外安排命令在给定延迟后运行，或定期执行。此外，它还提供了ThreadPoolExecutor的额外灵活性和功能。
下面是一个使用普通功能的示例。
创建执行器服务: final ScheduledExecutorService SCHEDULER = executors . newscheduleledthreadpool (1); 只需安排你的runnable: 最后未来< ?> future = SCHEDULER。schedule(可运行任务，长延迟，TimeUnit单元); 你现在可以使用future来取消任务或检查任务是否完成，例如: future.isDone ();
希望你会发现这对在Android中创建任务有用。
完整的例子:
ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
Future<?> sampleFutureTimer = scheduler.schedule(new Runnable(), 120, TimeUnit.SECONDS);
if (sampleFutureTimer.isDone()){
// Do something which will save world.
}
好的，因为这还没有清除，有3个简单的方法来处理这个。 下面的示例显示了所有3种方法，底部的示例显示了我认为更可取的方法。还记得在onPause中清理你的任务，如有必要保存状态。
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Handler.Callback;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class main extends Activity {
TextView text, text2, text3;
long starttime = 0;
//this posts a message to the main thread from our timertask
//and updates the textfield
final Handler h = new Handler(new Callback() {
@Override
public boolean handleMessage(Message msg) {
long millis = System.currentTimeMillis() - starttime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
text.setText(String.format("%d:%02d", minutes, seconds));
return false;
}
});
//runs without timer be reposting self
Handler h2 = new Handler();
Runnable run = new Runnable() {
@Override
public void run() {
long millis = System.currentTimeMillis() - starttime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
text3.setText(String.format("%d:%02d", minutes, seconds));
h2.postDelayed(this, 500);
}
};
//tells handler to send a message
class firstTask extends TimerTask {
@Override
public void run() {
h.sendEmptyMessage(0);
}
};
//tells activity to run on ui thread
class secondTask extends TimerTask {
@Override
public void run() {
main.this.runOnUiThread(new Runnable() {
@Override
public void run() {
long millis = System.currentTimeMillis() - starttime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
text2.setText(String.format("%d:%02d", minutes, seconds));
}
});
}
};
Timer timer = new Timer();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
text = (TextView)findViewById(R.id.text);
text2 = (TextView)findViewById(R.id.text2);
text3 = (TextView)findViewById(R.id.text3);
Button b = (Button)findViewById(R.id.button);
b.setText("start");
b.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Button b = (Button)v;
if(b.getText().equals("stop")){
timer.cancel();
timer.purge();
h2.removeCallbacks(run);
b.setText("start");
}else{
starttime = System.currentTimeMillis();
timer = new Timer();
timer.schedule(new firstTask(), 0,500);
timer.schedule(new secondTask(), 0,500);
h2.postDelayed(run, 0);
b.setText("stop");
}
}
});
}
@Override
public void onPause() {
super.onPause();
timer.cancel();
timer.purge();
h2.removeCallbacks(run);
Button b = (Button)findViewById(R.id.button);
b.setText("start");
}
}
要记住的主要事情是，UI只能从主UI线程修改，所以使用处理程序或活动。
以下是我认为最好的方法。
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class TestActivity extends Activity {
TextView timerTextView;
long startTime = 0;
//runs without a timer by reposting this handler at the end of the runnable
Handler timerHandler = new Handler();
Runnable timerRunnable = new Runnable() {
@Override
public void run() {
long millis = System.currentTimeMillis() - startTime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
timerTextView.setText(String.format("%d:%02d", minutes, seconds));
timerHandler.postDelayed(this, 500);
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_activity);
timerTextView = (TextView) findViewById(R.id.timerTextView);
Button b = (Button) findViewById(R.id.button);
b.setText("start");
b.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Button b = (Button) v;
if (b.getText().equals("stop")) {
timerHandler.removeCallbacks(timerRunnable);
b.setText("start");
} else {
startTime = System.currentTimeMillis();
timerHandler.postDelayed(timerRunnable, 0);
b.setText("stop");
}
}
});
}
@Override
public void onPause() {
super.onPause();
timerHandler.removeCallbacks(timerRunnable);
Button b = (Button)findViewById(R.id.button);
b.setText("start");
}
}
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