我有一个简单的秒表代码 fragment 。线程在自定义类中运行,它通过接口(interface)连接到主 Activity
public class MainActivity extends AppCompatActivity implements MainActivityInteractionInterface{
public static boolean isRunning = false;
Stopwatch stopWatch;
private TextView textViewMilliSeconds;
private TextView textViewSeconds;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textViewMilliSeconds = findViewById(R.id.textViewStopwatchMilliseconds);
textViewSeconds = findViewById(R.id.textViewStopwatchSeconds);
stopWatch = new Stopwatch(this, getApplicationContext());
stopWatch.runThread();
}
@Override
public void updateUI() {
String time = String.format(Locale.getDefault(), "%03d", stopWatch.getMilliseconds());
textViewMilliSeconds.setText(time);
String timeSeconds = String.format(Locale.getDefault(), "%02d", stopWatch.getSeconds());
textViewSeconds.setText(timeSeconds);
}
public void startTimer(View view) {
isRunning = !isRunning;
}
<小时/>
public class Stopwatch {
private int milliseconds = 0;
private int seconds = 0;
public int getMilliseconds() {
return milliseconds;
}
public int getSeconds() {
return seconds;
}
private MainActivityInteractionInterface interactionInterface;
private Context applicationContext;
public Stopwatch(MainActivityInteractionInterface interactionInterface, Context applicationContext){
this.interactionInterface = interactionInterface;
this.applicationContext = applicationContext;
}
public void runThread(){
final Handler handler = new Handler();
handler.post(new Runnable(){
@Override
public void run(){
if(isRunning) {
milliseconds++;
if (milliseconds == 1000) {
milliseconds = 0;
seconds++;
if(seconds == 60){
seconds = 0;
}
}
}
interactionInterface.updateUI();
handler.postDelayed(this, 1);
}
});
}
handler应该每1毫秒更新一次,当有1000毫秒时,1秒就过去了 如果我将 handler.postDelayed 延迟设置为低于 15 达到 1000 毫秒,则需要 18 秒,为什么?
最佳答案
我不知道为什么需要长达 18 秒的时间,但我可以告诉你:Android 每 16 毫秒刷新一次 UI(速率为 60fps),因此将处理程序设置为 updateUI 在更短的时间内就没有任何意义,而且可能还会干扰它。
以我的拙见,使其在 20 毫秒内更新并根据情况更改计数器值,如下所示:
handler.post(new Runnable(){
@Override
public void run(){
if(isRunning) {
milliseconds++;
if (milliseconds == 50) {
milliseconds = 0;
seconds++;
if(seconds == 60){
seconds = 0;
}
}
}
interactionInterface.updateUI();
handler.postDelayed(this, 20);
}
});
关于java - handler.postDelayed 无法正常工作,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61042358/