Java Integer Parse tryParseInt(String num)

Description

try Parse Int

License

Apache License

Declaration

public static Integer tryParseInt(String num) 

Method Source Code

//package com.java2s;
/*//from  ww w.  java2s  .c  o m
 * Copyright 2017 Google Inc.
 *
 * 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.
 */

public class Main {
    public static Integer tryParseInt(String num) {
        if (num.length() > 11 || num.length() == 0) {
            return null;
        }
        int i = 0;
        boolean negative = false;
        if (num.charAt(0) == '-') {
            if (num.length() == 1) {
                return null;
            }
            negative = true;
            i = 1;
        }
        // long to prevent overflow
        long number = 0;
        while (i < num.length()) {
            char c = num.charAt(i);
            if (c < '0' || c > '9') {
                return null;
            }
            number = number * 10 + (c - '0');
            i++;
        }
        if (negative) {
            if (-number < Integer.MIN_VALUE) {
                return null;
            } else {
                return (int) (-number);
            }
        } else {
            if (number > Integer.MAX_VALUE) {
                return null;
            }
            return (int) number;
        }
    }
}

Related

1. tryParseInt(Object o)
2. tryParseInt(Object obj, Integer defaultVal)
3. tryParseInt(String intString, int defaultValue)
4. tryParseInt(String s)
5. tryParseInt(String str)
6. tryParseInt(String str, int defaultValue)
7. tryParseInt(String stringInt)