在外部存儲的文件中寫入虛擬內容android

Question

在下面提到的代碼中，我將虛擬內容寫入名爲「testfile.txt」的文件中。但我想在外部存儲的任何文件中編寫虛擬內容。我不希望文件名被硬編碼。我該怎麼做？

String root = android.os.Environment.getExternalStorageDirectory().getPath(); 
File myFile = new File(root,"testfile.txt"); 

FileChannel rwChannel = new RandomAccessFile(myFile, "rw").getChannel(); 
int numBytes = (int)rwChannel.size(); 
ByteBuffer buffer = rwChannel.map(FileChannel.MapMode.READ_WRITE, 0, numBytes); 
System.out.println("buffer"+buffer); 
byte[] randomBytes = new byte[numBytes]; 
new Random().nextBytes(randomBytes); 
buffer.put(randomBytes); 
rwChannel.write(buffer); 
rwChannel.close(); 

Answer 1

File root = android.os.Environment.getExternalStorageDirectory(); 
File[] files = root.listFiles(); 
for (File f : files) { 
    if (f.isDirectory()) 
     continue; 
    //write here 
}