java For循环中的Android postDelayed处理程序？
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Android postDelayed Handler Inside a For Loop?
提问by Ivan Juarez
Is there any way of running a handler inside a loop? I have this code but is not working as it does not wait for the loop but executes the code right way:
有没有办法在循环内运行处理程序？我有这段代码，但没有工作，因为它不等待循环而是以正确的方式执行代码：
final Handler handler = new Handler();
final Runnable runnable = new Runnable() {
public void run() {
// need to do tasks on the UI thread
Log.d(TAG, "runn test");
//
for (int i = 1; i < 6; i++) {
handler.postDelayed(this, 5000);
}
}
};
// trigger first time
handler.postDelayed(runnable, 0);
Of course when I move the post delayed outside the loop works but it does not iterate nor execute the times I need:
当然，当我在循环之外移动延迟的帖子时，但它不会迭代或执行我需要的时间：
final Handler handler = new Handler();
final Runnable runnable = new Runnable() {
public void run() {
// need to do tasks on the UI thread
Log.d(TAG, "runn test");
//
for (int i = 1; i < 6; i++) {
}
// works great! but it does not do what we need
handler.postDelayed(this, 5000);
}
};
// trigger first time
handler.postDelayed(runnable, 0);
SOLUTION FOUND:
找到的解决方案：
I need to use asyntask along with Thread.sleep(5000) in the doInBackground method:
我需要在 doInBackground 方法中使用 asyntask 和 Thread.sleep(5000) ：
class ExecuteAsyncTask extends AsyncTask<Object, Void, String> {
//
protected String doInBackground(Object... task_idx) {
//
String param = (String) task_idx[0];
//
Log.d(TAG, "xxx - iter value started task idx: " + param);
// stop
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
//
Log.d(TAG, "xxx - iter value done " + param);
return " done for task idx: " + param;
}
//
protected void onPostExecute(String result) {
Log.d(TAG, "xxx - task executed update ui controls: " + result);
}
}
for(int i = 0; i < 6; i ++){
//
new ExecuteAsyncTask().execute( String.valueOf(i) );
}
回答by Shaishav
Instead of using a forloop, you can let the Runnableinstance call itself for a specific number of times. These calls will be posted to UI thread queue so, keep that in mind. Also, since the delay is quite large, make sure the event is still needed when you trigger it next time.
for您可以让Runnable实例调用自身特定次数，而不是使用循环。这些调用将发布到 UI 线程队列，因此请记住这一点。另外，由于延迟相当大，请确保下次触发时仍然需要该事件。
The following code should do it:
下面的代码应该这样做：
final Handler handler = new Handler();
int count = 0;
final Runnable runnable = new Runnable() {
public void run() {
// need to do tasks on the UI thread
Log.d(TAG, "Run test count: " + count);
if (count++ < 5) {
handler.postDelayed(this, 5000);
}
}
};
// trigger first time
handler.post(runnable);
回答by Androidz
My solution to this problem if anyone has simmilar issues:
如果有人遇到类似问题，我对此问题的解决方案是：
int count = 0;
public static void method(param1, param2, param3) {
Runnable r = () -> { //put method inside runnable
View view = listView.getChildAt(position); //action to be complete
if (view != null) { //if action is successfully complete
view.setSelected(true); //do something with this
} else { //do a looper
if (count < 10) { //limited looper to certain number
count++;
method(param1, param2, param3); //run the method again
}
};
Handler h = new Handler(); //create a new Handler and post above thread with it
h.postDelayed(r, 300);
}
Basically, I have created an if-else statement where else statement runs the same method with postDelayed()again for a limited number of trials.
基本上，我创建了一个 if-else 语句，其中 else 语句postDelayed()再次运行相同的方法以进行有限次数的试验。
回答by Hasan El-Hefnawy
This can be another solution
这可以是另一种解决方案
final Handler handler = new Handler();
Runnable runnable = new Runnable() {
int i;
public void run() {
for (i = 1; i < 6; i++) {
handler.postDelayed(new Runnable() {
@Override
public void run() {
// need to do tasks on the UI thread
Log.d(TAG, "runn test");
}
}, 0);
//Add some downtime
SystemClock.sleep(5000);
}
}
};
new Thread(runnable).start();
