StringUtils.java

package net.basilwang.utils;

public class StringUtils {
	/**
	 * <p>
	 * Checks if a CharSequence is empty ("") or null.
	 * </p>
	 * 
	 * <pre>
	 * StringUtils.isEmpty(null)      = true
	 * StringUtils.isEmpty("")        = true
	 * StringUtils.isEmpty(" ")       = false
	 * StringUtils.isEmpty("bob")     = false
	 * StringUtils.isEmpty("  bob  ") = false
	 * </pre>
	 * 
	 * 
	 * @param cs
	 *            the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is empty or null
	 */
	public static boolean isEmpty(CharSequence cs) {
		return cs == null || cs.length() == 0;
	}

	/**
	 * <p>
	 * Checks if a CharSequence is not empty ("") and not null.
	 * </p>
	 * 
	 * <pre>
	 * StringUtils.isNotEmpty(null)      = false
	 * StringUtils.isNotEmpty("")        = false
	 * StringUtils.isNotEmpty(" ")       = true
	 * StringUtils.isNotEmpty("bob")     = true
	 * StringUtils.isNotEmpty("  bob  ") = true
	 * </pre>
	 * 
	 * @param cs
	 *            the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is not empty and not null
	 */
	public static boolean isNotEmpty(CharSequence cs) {
		return !StringUtils.isEmpty(cs);
	}

	/**
	 * <p>
	 * Checks if a CharSequence is whitespace, empty ("") or null.
	 * </p>
	 * 
	 * <pre>
	 * StringUtils.isBlank(null)      = true
	 * StringUtils.isBlank("")        = true
	 * StringUtils.isBlank(" ")       = true
	 * StringUtils.isBlank("bob")     = false
	 * StringUtils.isBlank("  bob  ") = false
	 * </pre>
	 * 
	 * @param cs
	 *            the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is null, empty or whitespace
	 */
	public static boolean isBlank(CharSequence cs) {
		int strLen;
		if (cs == null || (strLen = cs.length()) == 0) {
			return true;
		}
		for (int i = 0; i < strLen; i++) {
			if (Character.isWhitespace(cs.charAt(i)) == false) {
				return false;
			}
		}
		return true;
	}

	/**
	 * <p>
	 * Checks if a CharSequence is not empty (""), not null and not whitespace
	 * only.
	 * </p>
	 * 
	 * <pre>
	 * StringUtils.isNotBlank(null)      = false
	 * StringUtils.isNotBlank("")        = false
	 * StringUtils.isNotBlank(" ")       = false
	 * StringUtils.isNotBlank("bob")     = true
	 * StringUtils.isNotBlank("  bob  ") = true
	 * </pre>
	 * 
	 * @param cs
	 *            the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is not empty and not null and
	 *         not whitespace
	 */
	public static boolean isNotBlank(CharSequence cs) {
		return !StringUtils.isBlank(cs);
	}
}