Deleting Files from Android SDCard

Today I needed to delete a bunch of files off of my phone because some rogue test program I was running generated several hundred image files in the root of my SDCard. Here is program I wrote to get rid of them:

package com.example.android.filemanagement;

import java.io.File;
import java.io.FilenameFilter;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class FileCleanupActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

       Button b = (Button) findViewById(R.id.go);
        b.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {

				// Delete those files!
		        Iterator it = listFiles().iterator();
		        while (it.hasNext()){
		        	it.next().delete();
		        }
				
			}
        });
        
        TextView tv = (TextView) findViewById(R.id.file_list);
        
        StringBuffer sb = new StringBuffer();
        Iterator it = listFiles().iterator();
        while (it.hasNext()){
        	sb.append(it.next().getName() + "\n");
        }
        
        tv.setText(sb.toString());
    }
    
    private static List listFiles(){
    	
    	File[] files = Environment.getExternalStorageDirectory()
    					.listFiles(new ExtensionFilter("jpg"));
    	
    	return Arrays.asList(files);
    }
}

class ExtensionFilter implements FilenameFilter {

	private String ext;
	
	public ExtensionFilter(String ext){
		this.ext = "."+ext;
	}
	
	@Override
	public boolean accept(File dir, String filename) {
		return filename.endsWith(ext);
	}
	
}