求助一个问题 ProgressDialog

Question

代码片段：case R.id.btn5:

//为什么这里 不需要handler呢  
Log.i("ThreadTest", Thread.currentThread().getName());
final ProgressDialog progressDialog = new ProgressDialog(this);
progressDialog.setIcon(R.drawable.icon);
progressDialog.setMax(100);
progressDialog.setTitle("loading");
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
//progressDialog.setSecondaryProgress(100);
progressDialog.show();

//又开了一个子线程
new Thread(){
public void run() {
int progress =0;
while(progress++<=100){
try {
Thread.sleep(200);
} catch (InterruptedException e) {

e.printStackTrace();
}
progressDialog.incrementProgressBy(1);
progressDialog.incrementSecondaryProgressBy(2);
}
Log.i("ThreadTest", Thread.currentThread().getName());
progressDialog.dismiss();
//textView.setText("xiazai wan bi");


};
}.start();
break;在子线程中：progressDialog调用incrementProgressBy() 这个方法 竟然能更新 ProgressDialog 这是什么情况。。不是说只有主线程才能更新界面吗。？望高人点拨一下。是不是我对Activity概念没有弄清楚。。

Answer 1

 progressDialog.incrementProgressBy(1);
 
  把这个换成progressDialog.setProgress(progressDialog.getProgress()+1)看看

Answer 2

这个要看源码是怎么更新的了，首先判断mUiThreadId == Thread.currentThread().getId()) 是不是ui线程是则直接刷新，不是的话是用Post来刷新的不是直接刷。所以概念上是没冲突的。
    private synchronized void refreshProgress(int id, int progress, boolean fromUser) {
        if (mUiThreadId == Thread.currentThread().getId()) {
            doRefreshProgress(id, progress, fromUser);
        } else {
            RefreshProgressRunnable r;
            if (mRefreshProgressRunnable != null) {
                // Use cached RefreshProgressRunnable if available
                r = mRefreshProgressRunnable;
                // Uncache it
                mRefreshProgressRunnable = null;
                r.setup(id, progress, fromUser);
            } else {
                // Make a new one
                r = new RefreshProgressRunnable(id, progress, fromUser);
            }
            post(r);
        }
    }

Answer 3

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