Class StringUtils

src/main/java/org/apache/commons/lang3/StringUtils.java:126–9370

 */
//@Immutable
public class StringUtils {

    // Performance testing notes (JDK 1.4, Jul03, scolebourne)
    // Whitespace:
    // Character.isWhitespace() is faster than WHITESPACE.indexOf()
    // where WHITESPACE is a string of all whitespace characters
    //
    // Character access:
    // String.charAt(n) versus toCharArray(), then array[n]
    // String.charAt(n) is about 15% worse for a 10K string
    // They are about equal for a length 50 string
    // String.charAt(n) is about 4 times better for a length 3 string
    // String.charAt(n) is best bet overall
    //
    // Append:
    // String.concat about twice as fast as StringBuffer.append
    // (not sure who tested this)

    /**
     * This is a 3 character version of an ellipsis. There is a Unicode character for a HORIZONTAL ELLIPSIS, U+2026 '…', this isn't it.
     */
    private static final String ELLIPSIS3 = "...";

    /**
     * A String for a space character.
     *
     * @since 3.2
     */
    public static final String SPACE = " ";

    /**
     * The empty String {@code ""}.
     *
     * @since 2.0
     */
    public static final String EMPTY = "";

    /**
     * The null String {@code null}. Package-private only.
     */
    static final String NULL = null;

    /**
     * A String for linefeed LF ("\n").
     *
     * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences
     *      for Character and String Literals</a>
     * @since 3.2
     */
    public static final String LF = "\n";

    /**
     * A String for carriage return CR ("\r").
     *
     * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences
     *      for Character and String Literals</a>
     * @since 3.2
     */