Here you can find the source of mkdir(String dir, String file)
public static File mkdir(String dir, String file)
//package com.java2s; //License from project: Apache License import java.io.File; public class Main { public static File mkdir(String dir, String file) { if (dir == null) throw new IllegalArgumentException("dir must be not null"); File result = new File(dir, file); parnetMkdir(result);/*from ww w . j a v a2s . c o m*/ return result; } public static void parnetMkdir(File outputFile) { if (outputFile.getParentFile() != null) { outputFile.getParentFile().mkdirs(); } } }