(android) 进度条ProgressBar的使用

main.xml 文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
<ProgressBar
 android:id="@+id/firstBar"
 android:layout_height="wrap_content"
 android:layout_width="200dp"
 android:visibility="gone"
 style="?android:attr/progressBarStyleHorizontal"
 />
 <ProgressBar
 android:id="@+id/secondBar"
 android:layout_height="wrap_content"
 android:layout_width="wrap_content"
 android:visibility="gone"
    style="?android:attr/progressBarStyle"
 />
<Button
 android:id="@+id/btn"
 android:layout_height="wrap_content"
 android:layout_width="wrap_content"
 android:text="ok"
 />
</LinearLayout>

.java 文件

package org.ProgressBarTest;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;

public class ProgressBarTest extends Activity {
    /** Called when the activity is first created. */
 private ProgressBar firstBar;
 private ProgressBar secondBar;
 private Button btn;
 private int i=0;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        firstBar=(ProgressBar)findViewById(R.id.firstBar);
        secondBar=(ProgressBar)findViewById(R.id.secondBar);
        btn=(Button)findViewById(R.id.btn);
        System.out.println("ssss");
        btn.setOnClickListener(new btnOnClickListener());
    }
    class btnOnClickListener implements OnClickListener{

  @Override
  public void onClick(View v) {
   
   // TODO Auto-generated method stub
   if(i==0)
   {
       firstBar.setVisibility(View.VISIBLE);
       secondBar.setVisibility(View.VISIBLE);
   }
   else if(i<firstBar.getMax())
   {
    firstBar.setProgress(i);
    firstBar.setSecondaryProgress(2*i);
   }
   else
   {
       firstBar.setVisibility(View.GONE);
       secondBar.setVisibility(View.GONE);
   }
   i+=10;
   System.out.println(i);
  }}
}