Here you can find the source of mkdirs(File dir)
public static void mkdirs(File dir) throws IOException
//package com.java2s; /**//from ww w .j a v a 2 s . com * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.io.*; public class Main { public static void mkdirs(File dir) throws IOException { if (dir.exists()) { if (!dir.isDirectory()) { throw new IOException( "Failed to create directory '" + dir + "', regular file already existed with that name"); } } else { if (!dir.mkdirs()) { throw new IOException("Failed to create directory '" + dir + "'"); } } } }