Android ProgressBar 进度条

 1.首先写一个进度条                  <ProgressBar                    android:id="@+id_mian_a"                    style="?android:attr/progressBarStyleHorizontal"                    android:layout_width="match_parent"                     android:layout_height="wrap_content" /> 2.再弄一个按钮，再在按钮里定义一个方法                <Button                      android:layout_width="wrap_content"                      android:layout_height="wrap_content"                      android:text="下载"                      android:onClick="xz"/> 再下一步在子线程中发消息  class MyThread extends Thread{         @Override         public void run() {             super.run();             for (int i = 0; i <=100 ; i++) {                 pb_progressbar_bar.setProgress(i);                // tv_progressbar_num.setText(i+"");                 //在子线程中发消息                 handler.sendEmptyMessage(i);                 try {                     Thread.sleep(100);                 } catch (InterruptedException e) {                     e.printStackTrace();                 }             }         }     } 调线程的方法    public void download(View view){         new MyThread().start();     }     Handler handler=new Handler(){         //接受消息，更新UI界面         @Override         public void handleMessage(Message msg) {             super.handleMessage(msg);             int i=msg.what;             tv_progressbar_num.setText(i+"");         }     }; 效果如下: 1.1 1.2 1.3