我一直在尝试创建一个程序，输出一个工作的数字时钟，这将允许我快速访问日期和时间。我有解析时间的代码，但是，我在更新textview时遇到了困难。我有这个：
`public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
timer = (TextView)findViewById(R.id.timer);
time = new Time();
time.setToNow();
timeString = time.toString();
changeTime = Parser(timeString);
time.setToNow();
timeString = time.toString();
changeTime = Parser(timeString);
timer.setText(changeTime);
}
private String Parser(String time){
String year = time.substring(0, 4);
String month = time.substring(4,6);
String day = time.substring(6, 8);
String hour = time.substring(9,11);
String minute = time.substring(11, 13);
String second = time.substring(13, 15);
String finalTime = hour + ":" + minute + ":" + second + " " + day + " " + month + " " + year;
//String finalTime = second;
return finalTime;
}`
如何将其置于循环中以不断更新textview。
感谢你给与我的帮助。
声明一个Handler来更新UI线程上的TextView。
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
time = new Time();
time.setToNow();
timeString = time.toString();
changeTime = Parser(timeString);
timer.setText(changeTime);
}
};
启动一个将更新TextView的TimeTask
int initialDelay = 1000; //first update in miliseconds
int period = 5000; //nexts updates in miliseconds
Timer timer = new Timer();
TimerTask task = new TimerTask() {
public void run() {
Message msg = new Message();
mHandler.sendMessage(msg);
}
};
timer.scheduleAtFixedRate(task, initialDelay, period);
你应该使用一个计时器线程。您还可以使用Calendar简化时间和日期转换，并可以使用format优化字符串创建。此示例将每秒更新您的TextView（1000毫秒）：
Timer t = new Timer();
timer = (TextView)findViewById(R.id.timer);
t.scheduleAtFixedRate(new TimerTask()
{
@Override
public void run() {
Calendar c = Calendar.getInstance();
final String finalTime = String.format(Locale.US, "%d:%d:%d %d/%d/%d", c.get(Calendar.HOUR), c.get(Calendar.MINUTE), c.get(Calendar.SECOND), c.get(Calendar.DAY_OF_MONTH), c.get(Calendar.MONTH), c.get(Calendar.YEAR));
runOnUiThread(new Runnable() {
@Override
public void run() {
timer.setText(finalTime);
}
});
}
}, 1000, 1000); //Initial Delay and Period for update (in milliseconds)
这可以通过android中的一个线程轻松完成，但是因为你想访问ui所以线程无法帮助你。你最好选择处理程序或timertask
但是，异步任务也在非ui线程上运行，因此在timertask中创建一个处理程序。
Timer t=Timer();
t.scheduleAtFixedRate(new TimerTask(new Runnable()
{
public void run(){
Handler h=new Handler(getMainLooper());
h.post(new Runnable(
){public void run(){
//get the time here and set the textview here as here it has access to the main ui
}});
}
}
), long delay, Long period);
对不起代码格式错误...但它会对你有用
使用永不结束的处理程序消息开始更新视图是一种不好的做法（尝试查看进程的CPU级别）。更好，更优雅的方式是注册一个触发更新的BroadcastReceiver。
public class Clock extends LinearLayout {
private Calendar mCalendar;
private LinearLayout mLayoutTime;
private TextView mAMPMText;
private TextView mDateText;
private TextView mTimeText;
private View mSendFeedback;
private boolean mAttached;
private final Handler mHandler = new Handler();
SimpleDateFormat dateFormatter = new SimpleDateFormat("EEE, MMM d, yyyy");
SimpleDateFormat timeFormatter = new SimpleDateFormat("h:mm");
public Clock(final Context context, int layoutResourceID, int dateResId, int meResId,int amPmResId) {
super(context);
LayoutInflater layoutInflater = LayoutInflater.from(context);
View view = layoutInflater.inflate(layoutResourceID, null);
addView(view, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
mAMPMText = (TextView) view.findViewById(amPmResId);
mTimeText = (TextView) view.findViewById(timeResId);
mDateText = (TextView) view.findViewById(dateResId);
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
if (!mAttached) {
mAttached = true;
IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_TIME_TICK);
filter.addAction(Intent.ACTION_TIME_CHANGED);
filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);
getContext().registerReceiver(mIntentReceiver, filter, null, mHandler);
}
// NOTE: It's safe to do these after registering the receiver since the receiver always runs
// in the main thread, therefore the receiver can't run before this method returns.
// The time zone may have changed while the receiver wasn't registered, so update the Time
mCalendar = Calendar.getInstance();
// Make sure we update to the current time
onTimeChanged();
updateView();
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mAttached) {
getContext().unregisterReceiver(mIntentReceiver);
mAttached = false;
}
}
private void updateView(){
mTimeText.setText(timeFormatter.format(mCalendar.getTime()));
mDateText.setText(dateFormatter.format(mCalendar.getTime()));
mAMPMText.setText(mCalendar.get(Calendar.AM_PM) == 0 ? "AM" : "PM");
}
private void onTimeChanged() {
mCalendar.setTime(new Date());
updateContentDescription(mCalendar);
}
private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_TIMEZONE_CHANGED)) {
String tz = intent.getStringExtra("time-zone");
mCalendar.setTimeZone(TimeZone.getTimeZone(tz));
}
onTimeChanged();
updateView();
}
};
private void updateContentDescription(Calendar calendar) {
setContentDescription(calendar.toString());
}
}
布局（可以做得更好）
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:orientation="horizontal" >
<LinearLayout
android:id="@+id/layout_time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:id="@+id/time_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:includeFontPadding="true" />
<TextView
android:id="@+id/am_pm_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="AM" />
</LinearLayout>
<TextView
android:id="@+id/date_txt"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>