Checks if the String contains only unicode letters or digits. null will return false. - Java java.lang

Java examples for java.lang:String Unicode

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Description

Checks if the String contains only unicode letters or digits. null will return false.

Demo Code

//package com.java2s;

public class Main {
    public static void main(String[] argv) {
        String str = "java2s.com";
        System.out.println(isAlphanumeric(str));
    }/* www .j  av  a  2 s.  co m*/

    /**
     * <p>Checks if the String contains only unicode letters or digits.</p>
     *
     * <p><code>null</code> will return <code>false</code>.
     * An empty String ("") will return <code>true</code>.</p>
     *
     * <pre>
     * isAlphanumeric(null)   = false
     * isAlphanumeric("")     = true
     * isAlphanumeric("  ")   = false
     * isAlphanumeric("abc")  = true
     * isAlphanumeric("ab c") = false
     * isAlphanumeric("ab2c") = true
     * isAlphanumeric("ab-c") = false
     * </pre>
     *
     * @param str  the String to check, may be null
     * @return <code>true</code> if only contains letters or digits,
     *  and is non-null
     */
    public static boolean isAlphanumeric(String str) {
        if (str == null) {
            return false;
        }
        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            if (Character.isLetterOrDigit(str.charAt(i)) == false) {
                return false;
            }
        }
        return true;
    }

    /**
     * Gets a String's length or <code>0</code> if the String is <code>null</code>.
     *
     * @param str
     *            a String or <code>null</code>
     * @return String length or <code>0</code> if the String is <code>null</code>.
     * @since 2.4
     */
    public static int length(String str) {
        return str == null ? 0 : str.length();
    }
}

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