Here you can find the source of count()
public static int count()
//package com.java2s; /******************************************************************************* * Copyright 2018 Johns Hopkins University * * 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./*from w w w .j a v a 2 s . c o m*/ * * This software was produced as part of the RMap Project (http://rmap-project.info), * The RMap Project was funded by the Alfred P. Sloan Foundation and is a * collaboration between Data Conservancy, Portico, and IEEE. *******************************************************************************/ import java.util.concurrent.atomic.AtomicInteger; public class Main { public static final AtomicInteger COUNTER = new AtomicInteger(); public static int count() { return COUNTER.getAndIncrement(); } }