Here you can find the source of isIntegerBigDecimal(BigDecimal bd)
static public boolean isIntegerBigDecimal(BigDecimal bd)
//package com.java2s; /*// w w w. j a v a2 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.math.BigDecimal; public class Main { /** * Tells if a {@link BigDecimal} stores a whole number. For example, it returns {@code true} for {@code 1.0000}, * but {@code false} for {@code 1.0001}. * * @since 2.3.21 */ static public boolean isIntegerBigDecimal(BigDecimal bd) { // [Java 1.5] Try to utilize BigDecimal.toXxxExact methods return bd.scale() <= 0 // A fast check that whole numbers usually (not always) match || bd.setScale(0, BigDecimal.ROUND_DOWN).compareTo(bd) == 0; // This is rather slow // Note that `bd.signum() == 0 || bd.stripTrailingZeros().scale() <= 0` was also tried for the last // condition, but stripTrailingZeros was slower than setScale + compareTo. } }