Turns a string into an int and returns a default value if unsuccessful. - Java java.lang

Java examples for java.lang:String Parse

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Description

Turns a string into an int and returns a default value if unsuccessful.

Demo Code


//package com.java2s;

public class Main {
    public static void main(String[] argv) {
        String s = "java2s.com";
        int def = 42;
        System.out.println(parseInt(s, def));
    }/*from ww w.j a  v a2s  .  c o m*/

    /** Turns a string into an int and returns a default value if unsuccessful.
     * @param s the string to convert
     * @param def the default value
     * @return the int value
     */
    public static int parseInt(String s, int def) {
        return parseInt(s, def, null, true);
    }

    /** Turns a string into an int and returns a default value if unsuccessful.
     * @param s the string to convert
     * @param def the default value
     * @param lastIdx sets lastIdx[0] to the index of the last digit
     * @param allowNegative if negative numbers are valid
     * @return the int value
     */
    public static int parseInt(String s, int def, final int[] lastIdx,
            final boolean allowNegative) {
        final boolean useLastIdx = lastIdx != null && lastIdx.length > 0;
        if (useLastIdx)
            lastIdx[0] = -1;

        if (s == null)
            return def;

        s = s.trim();
        if (s.length() == 0)
            return def;

        int firstDigit = -1;
        for (int i = 0; i < s.length(); i++) {
            if (Character.isDigit(s.charAt(i))) {
                firstDigit = i;
                break;
            }
        }

        if (firstDigit < 0)
            return def;

        int lastDigit = firstDigit + 1;
        while (lastDigit < s.length()
                && Character.isDigit(s.charAt(lastDigit)))
            lastDigit++;

        if (allowNegative && firstDigit > 0
                && s.charAt(firstDigit - 1) == '-')
            firstDigit--;

        if (useLastIdx)
            lastIdx[0] = lastDigit;
        return Integer.parseInt(s.substring(firstDigit, lastDigit));
    }
}

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