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POWhy does Handler::postDelay make UI frozen
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copied!<p>I have this code. I don't know why postDelay make UI frozen in this case. I want the Runnable will run after 100 miliseconds deley and run in 4000 miliseconds.</p> <pre><code>package com.delaythread; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ProgressBar; public class MyNeedActivity extends Activity implements OnClickListener { private ProgressBar progressBar; private final Handler handler = new Handler() { @Override public void handleMessage(final Message msg) { super.handleMessage(msg); progressBar.setVisibility(ProgressBar.INVISIBLE); } }; @Override public void onClick(final View v) { if(v.getId() == R.id.button1) { /* This call doesn't make ProgressBar frozen. final Thread t = new Thread(new MyRunnable()); t.start(); progressBar.setVisibility(ProgressBar.VISIBLE); */ // This makes ProgressBar frozen in 4000 miliseconds. final boolean b = handler.postDelayed(new MyRunnable(), 100); if(b) { progressBar.setVisibility(ProgressBar.VISIBLE); } } } /** Called when the activity is first created. */ @Override public void onCreate(final Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ((Button)findViewById(R.id.button1)).setOnClickListener(this); progressBar = (ProgressBar)findViewById(R.id.progressBar1); } private class MyRunnable implements Runnable { @Override public void run() { sleep(); } private void sleep() { try { Thread.sleep(4000); handler.sendEmptyMessage(0); } catch (final InterruptedException e) { e.printStackTrace(); } } } } </code></pre> <p><strong>Update</strong>: Actually what I want is AsyncTask executes after a delay time, so I do as this answer <a href="https://stackoverflow.com/questions/4177409/java-android-how-to-start-an-asynctask-after-3-seconds-of-delay">Java/android how to start an AsyncTask after 3 seconds of delay?</a>. He said I should use Handler and Runnable.</p>

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