Question

我想在我的应用程序屏幕上的标签中显示当前时间（小时：分钟）。

是否可以随着时间的变化自动更新？我的意思是，当分钟（和/或小时）改变时，我希望文本/标签自动更改它的值，而不必总是检查当前时间并更新它。

有人知道这是否可行？就像Android API中有一个特殊的“时间”对象一样连续显示它？

感谢。

编辑：如果我想要的是不可能的，你能否建议我一个精心设计的手动选择？

Answer 1

有人知道这是否可行？就好像有一个特殊的“时间” 来自Android API的对象连续显示它？

没有内置的东西，就像其他人说你会使用Handler并自己更新时间。请参阅下面的一个小例子：

private Handler mHandler = new Handler();
private TextView mText;// the TextView
private int mHour, mMinute; // variables holding the hour and minute
private Runnable mUpdate = new Runnable() {

    @Override
    public void run() {
        mMinute += 1;
        // just some checks to keep everything in order
        if (mMinute >= 60) {
            mMinute = 0;
            mHour += 1;
        }
        if (mHour >= 24) {
            mHour = 0; 
        }
        // or call your method
        mText.setText(mHour + ":" + mMinute);
        mHandler.postDelayed(this, 60000);
    }
};

@Override
protected void onResume() {
    super.onResume();
    // whenever the activity is built or resumed update the time and start posting updates
    Calendar c = Calendar.getInstance();
    mHour = c.get(Calendar.HOUR_OF_DAY);
    mMinute = c.get(Calendar.MINUTE);
    mText.setText(mHour + ":" + mMinute);
    mHandler.postDelayed(mUpdate, 60000); // 60000 a minute
}

@Override
protected void onStop() {
    super.onStop();
    mHandler.removeCallbacks(mUpdate);// we need to remove our updates if the activity isn't focused(or even destroyed) or we could get in trouble
    }

而不是setText()中的Runnable部分，您可以调用您的方法。

Answer 2

使用Luksprog的想法，我创建了一个文本视图，它是自我更新的Clock Text视图。

   import java.util.Calendar;

import android.content.Context;
import android.os.Handler;
import android.util.AttributeSet;
import android.widget.TextView;

public class TimerTextView extends TextView {

    private Handler mHandler = new Handler();
    private int mHour, mMinute, mSecond;// variables holding the hour and minute
    private Runnable mUpdate = new Runnable() {

        @Override
        public void run() {
            mSecond += 1;
            // just some checks to keep everything in order
            if (mSecond >= 60) {
                mSecond = 0;
                mMinute+=1;

            }
            if (mMinute >= 60) {
                mMinute = 0;
                mHour += 1;
            }
            if (mHour >= 24) {
                mHour = 0;
            }
            // or call your method
            setText(mHour + ":" + mMinute+":"+mSecond);
            mHandler.postDelayed(this, 1000);
        }
    };



    public TimerTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context) { 
        mHandler.removeCallbacks(mUpdate);
        Calendar c = Calendar.getInstance();
        mHour = c.get(Calendar.HOUR_OF_DAY);
        mMinute = c.get(Calendar.MINUTE);
        mSecond = c.get(Calendar.SECOND);
         setText(mHour + ":" + mMinute+":"+mSecond);
        mHandler.postDelayed(mUpdate, 1000); // 60000 a minute


    }

    public TimerTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public TimerTextView(Context context) {
        super(context);
        init(context);
    }

}

只需将此自定义Textview放入布局XML中即可。它会自动工作

Answer 3

不，虽然有人可能写了一个视图，但这并不是很难。我会简单地使用一个处理程序并向它发送延迟消息，该消息在1分钟后消失。当处理程序处理消息时，让它更新标签。然后让它自己发送另一条消息，再延迟一分钟。这样，只要您在前台并更新文本视图，就会每分钟调用一次。

Answer 4

如果您想要手动实现，可以使用handler和countDownTimer。处理程序将更新textviews，CountDownTimer将根据特定频率计算时间。

Answer 5

试试这段代码。。

public class MainActivity extends Activity  {

    TextView t;

    private Handler mHandler = new Handler();

    private int mHour, mMinute,mSecond; // variables holding the hour and minute

    String min,hr,sec;

    private Runnable mUpdate = new Runnable() {

        @Override
        public void run() {

             Calendar c = Calendar.getInstance();
             mHour = c.get(Calendar.HOUR_OF_DAY);
             mMinute = c.get(Calendar.MINUTE);
             mSecond = c.get(Calendar.SECOND);

               min = "" +mMinute;
          hr = "" +mHour;
          sec = "" +mSecond;
         if(min.length()==1 ){

             min = "0"+mMinute;

         }if(hr.length()==1){

             hr = "0" +mHour;

         }if(sec.length()==1){
             sec = "0" +mSecond;

         }
             t.setText(hr + ":" + min + ":" + sec);     

            mHandler.postDelayed(this, 1000);
        }
    };

    @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);


          t = (TextView)findViewById(R.id.textView1);

        }

      @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();

        Calendar c = Calendar.getInstance();
        mHour = c.get(Calendar.HOUR_OF_DAY);
        mMinute = c.get(Calendar.MINUTE);
        mSecond = c.get(Calendar.SECOND);
        t.setText(mHour + ":" + mMinute + ":" + mSecond);
        mHandler.postDelayed(mUpdate, 1000);
    }

      @Override
    protected void onStop() {
        // TODO Auto-generated method stub
        super.onStop();
         mHandler.removeCallbacks(mUpdate);
    }


    }

具有自我更新时间（小时和分钟）的Android标签

5 个答案: