是否已经有Android的StopWatch类,为什么我的实现不起作用？

Question

最近我看到http://developer.android.com/reference/android/os/CountDownTimer.html,并想知道是否有一个相应的秒表类,因为我想告诉用户我的应用程序他已经尝试解决了多长时间这个谜题.我的意思是自己编程这样的秒表并不复杂.我试过类似的东西

    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            while (true) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                }
                long seconds = (System.currentTimeMillis() - t) / 1000;
                statusBar.setText(String.format("%02d:%02d", seconds / 60, seconds % 60));
            }
        }

    };
    statusBar.post(runnable);

但奇怪的是我的活动的布局不再膨胀,因为我statusBar.post(runnable);在acitivity的onCreate方法结束时有这个意思,这意味着在启动应用程序后我只看到一个白色屏幕而不是正常的gui.

Answer 1

看看Chronometer课程.

来自APIDemo的示例代码:

import android.app.Activity;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Chronometer;

public class ChronometerDemo extends Activity {
    Chronometer mChronometer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.chronometer);

        Button button;

        mChronometer = (Chronometer) findViewById(R.id.chronometer);

        // Watch for button clicks.
        button = (Button) findViewById(R.id.start);
        button.setOnClickListener(mStartListener);

        button = (Button) findViewById(R.id.stop);
        button.setOnClickListener(mStopListener);

        button = (Button) findViewById(R.id.reset);
        button.setOnClickListener(mResetListener);

        button = (Button) findViewById(R.id.set_format);
        button.setOnClickListener(mSetFormatListener);

        button = (Button) findViewById(R.id.clear_format);
        button.setOnClickListener(mClearFormatListener);
    }

    View.OnClickListener mStartListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.start();
        }
    };

    View.OnClickListener mStopListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.stop();
        }
    };

    View.OnClickListener mResetListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.setBase(SystemClock.elapsedRealtime());
        }
    };

    View.OnClickListener mSetFormatListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.setFormat("Formatted time (%s)");
        }
    };

    View.OnClickListener mClearFormatListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.setFormat(null);
        }
    };
}

R.layout.chronometer:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:padding="4dip"
    android:gravity="center_horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Chronometer android:id="@+id/chronometer"
        android:format="@string/chronometer_initial_format"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:paddingBottom="30dip"
        android:paddingTop="30dip"
        />

    <Button android:id="@+id/start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="@string/chronometer_start">
        <requestFocus />
    </Button>

    <Button android:id="@+id/stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="@string/chronometer_stop">
    </Button>

    <Button android:id="@+id/reset"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="@string/chronometer_reset">
    </Button>

    <Button android:id="@+id/set_format"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="@string/chronometer_set_format">
    </Button>

    <Button android:id="@+id/clear_format"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="@string/chronometer_clear_format">
    </Button>

</LinearLayout>

将其添加到Strings.xml

<string name="chronometer_start">Start</string>
<string name="chronometer_stop">Stop</string>
<string name="chronometer_reset">Reset</string>
<string name="chronometer_set_format">Set format string</string>
<string name="chronometer_clear_format">Clear format string</string>
<string name="chronometer_initial_format">Initial format: <xliff:g id="initial-format">%s</xliff:g></string>

Answer 2

你应该使用天文台表.

但无论如何,如果从UI线程中删除睡眠,则代码可以正常工作.

private final Runnable mRunnable = new Runnable() {
    @Override
    public void run() {
        if (mStarted) {
            long seconds = (System.currentTimeMillis() - t) / 1000;
            statusBar.setText(String.format("%02d:%02d", seconds / 60, seconds % 60));
            handler.postDelayed(runnable, 1000L);
        }
    }

};

private Hanlder mHandler;
private boolean mStarted;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mHandler = new Handler();
}

@Override
protected void onStart() {
    super.onStart();
    mStarted = true;
    mHandler.postDealyed(runnable, 1000L);
}

@Override
protected void onStop() {
    super.onStop();
    mStarted = false;
    mHandler.removeCallbacks(mRunnable);
}

Answer 3

您应该使用Chronometer。

Chronometer mChronometer;
mChronometer = (Chronometer) findViewById(R.id.chronometer1);
long timeWhenStopped = 0;

当我们停止计时

timeWhenStopped = mChronometer.getBase() - SystemClock.elapsedRealtime();
mChronometer.stop();

启动前的计时器

mChronometer.setBase(SystemClock.elapsedRealtime() + timeWhenStopped);
mChronometer.start();

重置计时器

mChronometer.setBase(SystemClock.elapsedRealtime());
timeWhenStopped = 0;