我正在为一项活动制作定制的倒计时器，但我在切换活动时无法实时更新值。每次切换活动后，我只能更新一次值。
举个例子：
活动A -> B（屏幕上默认为0，用户将其更新为10）
B -> A ->（屏幕上为10，用户将其更新为10）
B -> A ->（屏幕上为35，用户将其更新为9000）等等
然而，一旦用户设置了时间，它应该不断更新并倒计时。
我可以通过Runnable在后台更新值并在控制台打印出值，但是我不知道为什么它不会持续地将值传回到先前的活动A（以便它处于最新状态），然后当用户返回B时由A将值传回B。
需要注意的是，当我尝试仅在run()中更新额外信息而不在updateTimerButton()中进行更新时，屏幕上什么都不会改变，只有默认值，但在幕后值正在更新（控制台）。
这是我的代码：
public class CustomTimer extends Activity {
private final Handler handler = new Handler();
private Intent intent;
private Button timerButton;
private EditText hourValue, minuteValue;
private long startTime = 0L;
private long timeInMilliseconds = 0L;
private long timeSwapBuff = 0L;
private long updatedTime = 0L;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_custom_timer);
intent = getIntent();
hourValue = (EditText) findViewById(R.id.hour_value);
minuteValue = (EditText) findViewById(R.id.minute_value);
timerButton = (Button) findViewById(R.id.start_timer_button);
//avoid grabbing values from hour and minute if they were not passed for some reason
if(intent.getStringExtra("hourValue") != null)
hourValue.setText(getIntent().getStringExtra("hourValue"));
if(intent.getStringExtra("minuteValue") != null)
minuteValue.setText(getIntent().getStringExtra("minuteValue"));
setUpHourValue();
setUpMinuteValue();
setUpTimerButton();
}
private void setUpHourValue(){
hourValue.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
hourValue.setText(v.getText().toString());
return false;
}
});
}
private void setUpMinuteValue(){
minuteValue.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
minuteValue.setText(v.getText().toString());
return false;
}
});
}
private void setUpTimerButton(){
timerButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String hourTime = hourValue.getText().toString();
String minuteTime = minuteValue.getText().toString();
//only start the timer if it is not zero
if (!hourTime.equals("00") || !minuteTime.equals("00")) {
System.out.println("starting runnable");
startTime = SystemClock.uptimeMillis();
handler.postDelayed(updateTimerThread, 0);
}
else{
System.out.println("time is default\t" + hourTime + " : " + minuteTime + "************");
}
//send the time values back to main
//this does not constantly update the values, it only updates it once
intent.putExtra("hourValue", hourTime);
intent.putExtra("minuteValue", minuteTime);
setResult(RESULT_OK, intent);
finish();//go back to the previous page
}
});
}
private Intent getOuterClassIntent(){
return intent;
}
private Runnable updateTimerThread = new Runnable() {
//update the time on the screen and constantly pass the values back to main
public void run() {
String hourTime = hourValue.getText().toString();
String minuteTime = minuteValue.getText().toString();
timeInMilliseconds = SystemClock.uptimeMillis() - startTime;
updatedTime = timeSwapBuff + timeInMilliseconds;
int secs = (int) (updatedTime / 1000);
int mins = secs / 60;
int hour = mins / 60;
secs = secs % 60;
//update the time on screen
hourValue.setText(Integer.toString(Integer.parseInt(hourTime) - hour));
minuteValue.setText(Integer.toString(Integer.parseInt(minuteTime) - secs));
System.out.println("updating time in runnable");
System.out.println(hourValue.getText().toString()+ " : " + minuteValue.getText().toString());
//pass the values back to main, but this does NOTHING if I comment out the previous putExtras (above)
getOuterClassIntent().putExtra("hourValue", hourTime);
getOuterClassIntent().putExtra("minuteValue", minuteTime);
setResult(RESULT_OK, getOuterClassIntent());
handler.postDelayed(this, 0);
}
};
}