【Java】输出目录结构

import java.io.*; 
import java.io.File;
import java.io.IOException;

public class FileUtil {
    
    public static void main( String[] args ) throws IOException {
        
        BufferedReader buffReader = new BufferedReader( new 
                                        InputStreamReader( System.in ) );
        
        
        System.out.println("input dir::");
        
        String str = buffReader.readLine();

        showDir( 1, new File(str) );
    }
    
    static void showDir( int idx, File file ) throws IOException {
        for( int i = 0; i < idx; i++ ) {
            System.out.print('-');
        }
            
        System.out.println( file.getName() );
        
        if( file.isDirectory() ) {
            File[] files = file.listFiles();
            //System.out.print('|');
            for( int j = 0; j < files.length; j++ ) {
                showDir( idx+4, files[j]);
            }
        }
    }
}