<?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"    style="?android:attr/progressBarStyleHorizontal"    android:layout_width="200dp"    android:layout_height="wrap_content"    android:visibility="gone"    /><ProgressBar    android:id="@+id/secondBar"    style="?android:attr/progressBarStyle"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:visibility="gone"    /><Button    android:id="@+id/myButton"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="begin"    /></LinearLayout>

package mars.progressbar;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. */    //声明变量    private ProgressBar firstBar =null;    private ProgressBar secondBar = null;    private Button myButton = null;    private int i = 0 ;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        //根据控件的ID来取得代表控件的对象        firstBar = (ProgressBar)findViewById(R.id.firstBar);        secondBar = (ProgressBar)findViewById(R.id.secondBar);        myButton = (Button)findViewById(R.id.myButton);        myButton.setOnClickListener(new ButtonListener());    }    class ButtonListener implements OnClickListener{                @Override        public void onClick(View v) {            if(i == 0)            {                //设置进度条处于可见的状态                firstBar.setVisibility(View.VISIBLE);                firstBar.setMax(150);                secondBar.setVisibility(View.VISIBLE);            }            else if ( i < firstBar.getMax()){                //设置主进度条的当前值                firstBar.setProgress(i);                //设置第二进度条的当前值                firstBar.setSecondaryProgress(i + 10);                //因为默认的进度条无法显示进行的状态                //secondBar.setProgress(i);                            }            else{                //设置进度条处于不可见状态                firstBar.setVisibility(View.GONE);                secondBar.setVisibility(View.GONE);            }            i = i + 10 ;        }            }    }