Here you can find the source of fileExists(File dir, String regex)
public static boolean fileExists(File dir, String regex)
//package com.java2s; /*//www . j a v a 2 s . c o m * Copyright 2017 Hortonworks. * * Licensed 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.File; import java.io.FileFilter; public class Main { public static boolean fileExists(File dir, String regex) { File[] files = dir.listFiles(new FileFilter() { public boolean accept(File pathname) { return pathname.getName().matches(regex); } }); return files != null && files.length == 1; } }