Android Int Overflow Check mulAndCheck(int x, int y)

Description

Multiply two integers, checking for overflow.

License

Apache License

Parameter

Parameter	Description
x	Factor.
y	Factor.

Exception

Parameter	Description
MathArithmeticException	if the result can not berepresented as an int.

Return

the product x * y .

Declaration

public static int mulAndCheck(int x, int y)
        throws MathArithmeticException 

Method Source Code

/*//  ww w . j a va 2s .c  o m
 * 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.BigInteger;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.commons.math3.exception.MathArithmeticException;
import org.apache.commons.math3.exception.NotPositiveException;
import org.apache.commons.math3.exception.NumberIsTooLargeException;
import org.apache.commons.math3.exception.util.Localizable;
import org.apache.commons.math3.exception.util.LocalizedFormats;

public class Main{
    /**
     * Multiply two integers, checking for overflow.
     *
     * @param x Factor.
     * @param y Factor.
     * @return the product {@code x * y}.
     * @throws MathArithmeticException if the result can not be
     * represented as an {@code int}.
     * @since 1.1
     */
    public static int mulAndCheck(int x, int y)
            throws MathArithmeticException {
        long m = ((long) x) * ((long) y);
        if (m < Integer.MIN_VALUE || m > Integer.MAX_VALUE) {
            throw new MathArithmeticException();
        }
        return (int) m;
    }
    /**
     * Multiply two long integers, checking for overflow.
     *
     * @param a Factor.
     * @param b Factor.
     * @return the product {@code a * b}.
     * @throws MathArithmeticException if the result can not be represented
     * as a {@code long}.
     * @since 1.2
     */
    public static long mulAndCheck(long a, long b)
            throws MathArithmeticException {
        long ret;
        if (a > b) {
            // use symmetry to reduce boundary cases
            ret = mulAndCheck(b, a);
        } else {
            if (a < 0) {
                if (b < 0) {
                    // check for positive overflow with negative a, negative b
                    if (a >= Long.MAX_VALUE / b) {
                        ret = a * b;
                    } else {
                        throw new MathArithmeticException();
                    }
                } else if (b > 0) {
                    // check for negative overflow with negative a, positive b
                    if (Long.MIN_VALUE / b <= a) {
                        ret = a * b;
                    } else {
                        throw new MathArithmeticException();

                    }
                } else {
                    // assert b == 0
                    ret = 0;
                }
            } else if (a > 0) {
                // assert a > 0
                // assert b > 0

                // check for positive overflow with positive a, positive b
                if (a <= Long.MAX_VALUE / b) {
                    ret = a * b;
                } else {
                    throw new MathArithmeticException();
                }
            } else {
                // assert a == 0
                ret = 0;
            }
        }
        return ret;
    }
}

Related

1. addAndCheck(int x, int y)
2. constrain(int value, int min, int max)
3. stirlingS2(final int n, final int k)
4. subAndCheck(int x, int y)
5. multiply(int x, int y)
6. multiply(int x, int y)