android开发学习笔记——简单的ProgressBar

本人android的菜鸟，如有错误还望各位大牛不吝赐教！

package com.example.progressbar;

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

public class MainActivity extends Activity {
private ProgressBar bar1;
private ProgressBar bar2;
private Button button1;
private int i=0;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bar1=(ProgressBar)findViewById(R.id.progressBar1);
bar2=(ProgressBar)findViewById(R.id.progressBar2);
button1=(Button)findViewById(R.id.dowmload);
System.out.println(bar1.getMax());
System.out.println(bar2.getMax());

}
//download 绑定下载按钮
public void download(View view) {
if(i==0){
bar1.setVisibility(view.VISIBLE);
bar2.setVisibility(view.VISIBLE);
}
else if (i<100) {
bar1.setProgress(i+10);
bar2.setSecondaryProgress(i+10);
}
else {
//下载完成之后显示的toast
Toast toast=Toast.makeText(MainActivity.this,"下载完成",Toast.LENGTH_SHORT);
toast.show();
}
//注意位置
i=i+10;
}
//exitprogram
public void exitprogram(View view){
System.exit(0);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<ProgressBar
android:id="@+id/progressBar2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/progressBar1"
android:layout_below="@+id/progressBar1"
android:layout_marginLeft="105dp"
android:layout_marginTop="34dp"
android:visibility="gone" />

<ProgressBar
android:id="@+id/progressBar1"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="40dp"
android:visibility="gone" />

<Button
android:id="@+id/dowmload"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="89dp"
android:onClick="download"
android:text="@string/button1" />

<Button
android:id="@+id/exitprogram"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/dowmload"
android:layout_alignParentBottom="true"
android:layout_marginBottom="45dp"
android:onClick="exitprogram"
android:text="@string/exitbutton" />

</RelativeLayout>