Java tutorial
//package com.java2s; /* * Copyright (c) 2016 Qiscus. * * 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; public class Main { public static String getExtension(File file) { return getExtension(file.getPath()); } public static String getExtension(String fileName) { int lastDotPosition = fileName.lastIndexOf("."); String ext = fileName.substring(lastDotPosition + 1); ext = ext.replace("_", ""); return ext.trim().toLowerCase(); } }