Here you can find the source of isInt(final BigInteger i)
public static boolean isInt(final BigInteger i)
//package com.java2s; /*-/*from w w w . java 2 s .c o m*/ * #%L * The MIT License (MIT) * %% * Copyright (C) 2016 - 2017 Vinz (https://github.com/gv2011) * %% * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. * #L% */ import java.math.BigInteger; public class Main { private static final BigInteger MIN_INT = BigInteger.valueOf(Integer.MIN_VALUE); private static final BigInteger MAX_INT = BigInteger.valueOf(Integer.MAX_VALUE); public static boolean isInt(final BigInteger i) { return i.compareTo(MIN_INT) >= 0 && i.compareTo(MAX_INT) <= 0; } }