package geeker.MyActivity;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;
public class MyActivity extends Activity {
  //成员变量的声明
  private TextView myTextView = null;
  private Button myButton = null;
  //重写OnCreate方法，会自动生成
  public void onCreate(Bundle savedInstanceState) {
    //调用父类方法，该句代码自动生成
    super.onCreate(savedInstanceState);
    //通过布局文件的id调用该Activity所使用的布局文件
    setContentView(R.layout.main);
    //通过findViewById（）方法拿到布局文件中添加的控件
    //不过在布局文件中添加控件的时候必须定义id号，
    //如：android:id="@+id/myTextView"
    myTextView = (TextView)findViewById(R.id.myTextView);
    myButton = (Button)findViewById(R.id.myButton);
    //向控件上制定显示文字
    myTextView.setText("This is my first Activity !");
    myButton.setText("MY FIRST BUTTON"); 
  }
}

<?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:id="@+id/myTextView"
  android:layout_width="fill_parent" 
  android:layout_height="wrap_content" 
  />
<Button
  android:id="@+id/myButton"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  />  
</LinearLayout>

/* AUTO-GENERATED FILE. DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found. It
 * should not be modified by hand.
 */
package geeker.MyActivity;
public final class R {
  public static final class attr {
  }
  public static final class drawable {
    public static final int icon=0x7f020000;
  }
  public static final class id {
    public static final int myButton=0x7f050001;
    public static final int myTextView=0x7f050000;
  }
  public static final class layout {
    public static final int main=0x7f030000;
  }
  public static final class string {
    public static final int app_name=0x7f040001;
    public static final int hello=0x7f040000;
  }
}

<Button
  android:id="@+id/myButton"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  />

public static final class id {
    public static final int myButton=0x7f050001;
    public static final int myTextView=0x7f050000;
  }

private Button myButton = null;
myButton = (Button)findViewById(R.id.myButton);
myButton.setText("MY FIRST BUTTON"); 

<activity android:name=".MyActivity"
         android:label="@string/app_name">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>

package net.nowamagic.file;
import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import android.util.Log;
/**
 * @author 
 * function 用于扫描SD卡上的文件
 *
 */
public class FileScan {
  
  private static final String TAG = "FileScan";
  public HashMap<String, String> getMusicListOnSys(File file) {
    
    //从根目录开始扫描
    Log.i(TAG, file.getPath());
    HashMap<String, String> fileList = new HashMap<String, String>();
    getFileList(file, fileList);
    return fileList;
  }
  
  /**
   * @param path
   * @param fileList
   * 注意的是并不是所有的文件夹都可以进行读取的，权限问题
   */
  private void getFileList(File path, HashMap<String, String> fileList){
    //如果是文件夹的话
    if(path.isDirectory()){
      //返回文件夹中有的数据
      File[] files = path.listFiles();
      //先判断下有没有权限，如果没有权限的话，就不执行了
      if(null == files)
        return;
      
      for(int i = 0; i < files.length; i++){
        getFileList(files[i], fileList);
      }
    }
    //如果是文件的话直接加入
    else{
      Log.i(TAG, path.getAbsolutePath());
      //进行文件的处理
      String filePath = path.getAbsolutePath();
      //文件名
      String fileName = filePath.substring(filePath.lastIndexOf("/")+1);
      //添加
      fileList.put(fileName, filePath);
    }
  }
  
}