@Override 
public void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.main); 
  EditText keywordText = (EditText)this.findViewById(R.id.keyword); 
  Button button = (Button)this.findViewById(R.id.button); 
  TextView result = (TextView)this.findViewById(R.id.result); 
  button.setOnClickListener(new Button.OnClickListener() { 
   public void onClick(View v) {
     String keyword = keywordText.getText().toString(); 
     if (keyword.equals("")) { 
       result.setText("请勿输入空白的关键词!!"); 
     }else { 
      result.setText(searchFile(keyword)); 
     } 
   } 
 }); 
}

private String searchFile(String keyword) { 
  String result = ""; 
  File[] files = new File("/").listFiles(); 
  for (File file : files) { 
   if (fike.getName().indexOf(keyword) >= 0) { 
    result += file.getPath() + "\n"; 
   } 
  } 
 if (result.equals("")){
  result = "找不到文件!!"; 
 }
 return result; 
}

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission> 

  Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED); 

File skRoot = Environment.getExternalStorageDirectory(); 

File fileRoot = Context.getFilesDir()+"\"; 

String path = File.getPath();//相对 
String path = File.getAbsoultePath();//绝对 

String parentPath = File.getParent(); 

String Name = File.getName(); 

File.mkDir(); //建立文件夹 
File.createNewFile();//建立文件 

File.isDirectory() 
File.isDirectory()

File[] files = File.listFiles(); 

File.renameTo(dest); 

File.delete();