Java Regex Number Validate isNumber(String value)

Description

is Number

License

Open Source License

Declaration

public static boolean isNumber(String value) 

Method Source Code

//package com.java2s;
// %InstallDIR%\features\org.talend.rcp.branding.%PRODUCTNAME%\%PRODUCTNAME%license.txt

import java.util.regex.Pattern;

public class Main {
    private static final Pattern patternInteger = Pattern.compile("^(\\+|-)?\\d+$");
    private static final Pattern patternDouble = Pattern.compile("^[-+]?"// Positive/Negative sign
            + "("// BEGIN Decimal part
            + "[0-9]+([,\\.][0-9]+)?|"// Alternative I (w/o grouped integer part)
            + "(" // BEGIN Alternative II (with grouped integer part)
            + "[0-9]{1,3}" // starting digits
            + "(" // BEGIN grouped part
            + "((,[0-9]{3})*"// US integer part
            + "(\\.[0-9]+)?"// US float part
            + "|" // OR
            + "((\\.[0-9]{3})*|([ \u00A0\u2007\u202F][0-9]{3})*)"// EU integer part
            + "(,[0-9]+)?)"// EU float part
            + ")"// END grouped part
            + ")" // END Alternative II
            + ")" // END Decimal part
            + "([ ]?[eE][-+]?[0-9]+)?$");

    public static boolean isNumber(String value) {
        return isDouble(value) || isInteger(value);

    }/*  ww w. j ava2  s  .  co m*/

    /**
     * Detect if the given value is a double type.
     * 
     * <p>
     * Note:<br>
     * 1. This method support only English locale.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("3.4")} returns {@code true}.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("3,4")} returns {@code false}.<br>
     * 2. Exponential notation can be detected as a valid double.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("1.0E+4")} returns {@code true}.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("1.0e-4")} returns {@code true}.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("1.0e-04")} returns {@code true}.<br>
     * 3. Numbers marked with a type is invalid.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("3.4d")} returns {@code false}.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("123L")} returns {@code false}.<br>
     * 4. White space is invalid.<br>
     * e.g. {@code TypeInferenceUtils.isDouble(" 3.4")} returns {@code false}.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("3.4 ")} returns {@code false}.<br>
     * 5. "." is not obligatory.<br>
     * e.g. {@code TypeInferenceUtils.isDouble("100")} returns {@code true}.
     * <P>
     * 
     * @param value the value to be detected.
     * @return true if the value is a double type, false otherwise.
     */
    public static boolean isDouble(String value) {
        if (!isEmpty(value) && patternDouble.matcher(value).matches()) {
            return true;
        }
        return false;
    }

    /**
     * Detect if the given value is a integer type.
     * 
     * @param value the value to be detected.
     * @return true if the value is a integer type, false otherwise.
     */
    public static boolean isInteger(String value) {
        if (!isEmpty(value) && patternInteger.matcher(value).matches()) {
            return true;
        }
        return false;
    }

    /**
     * Detect if the given value is blank or null.
     * 
     * @param value the value to be detected.
     * @return true if the value is blank or null, false otherwise.
     */
    public static boolean isEmpty(String value) {
        return value == null || value.trim().length() == 0;
    }
}

Related

1. isNumber(String str)
2. isNumber(String str)
3. isNumber(String str)
4. isNumber(String str, String sign)
5. isNumber(String value)
6. isNumber(String value)
7. isNumber_Lowerletter_Underline(String str)
8. isNumberForLength(String numStr, int length)
9. isNumberLiteral(String s)