Removes one newline from end of a String if it's there, otherwise leave it alone. - Java java.lang

Description

Removes one newline from end of a String if it's there, otherwise leave it alone.

Demo Code

/*/* w w  w .ja  v  a 2s.  c  o  m*/
 * Copyright 2013 Guidewire Software, Inc.
 */
/**
 * This class is based, in part, on org.apache.commons.lang.StringUtils and is intended
 * to break the dependency on that project.
 *
 * @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a>
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @author Daniel L. Rall
 * @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a>
 * @author <a href="mailto:ed@apache.org">Ed Korthof</a>
 * @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a>
 * @author Stephen Colebourne
 * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
 * @author Holger Krauth
 * @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>
 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
 * @author Arun Mammen Thomas
 * @author Gary Gregory
 * @author Phil Steitz
 * @author Al Chou
 * @author Michael Davey
 * @author Reuben Sivan
 * @author Chris Hyzer
 *  Johnson

 */
//package com.java2s;

public class Main {
    public static void main(String[] argv) {
        String str = "java2s.com  ";
        System.out.println(chomp(str));
    }

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

    /**
     * <p>Removes one newline from end of a String if it's there,
     * otherwise leave it alone.  A newline is &quot;<code>\n</code>&quot;,
     * &quot;<code>\r</code>&quot;, or &quot;<code>\r\n</code>&quot;.</p>
     *
     * <p>NOTE: This method changed in 2.0.
     * It now more closely matches Perl chomp.</p>
     *
     * <pre>
     * chomp(null)          = null
     * chomp("")            = ""
     * chomp("abc \r")      = "abc "
     * chomp("abc\n")       = "abc"
     * chomp("abc\r\n")     = "abc"
     * chomp("abc\r\n\r\n") = "abc\r\n"
     * chomp("abc\n\r")     = "abc\n"
     * chomp("abc\n\rabc")  = "abc\n\rabc"
     * chomp("\r")          = ""
     * chomp("\n")          = ""
     * chomp("\r\n")        = ""
     * </pre>
     *
     * @param str  the String to chomp a newline from, may be null
     * @return String without newline, <code>null</code> if null String input
     */
    public static String chomp(String str) {
        if (isEmpty(str)) {
            return str;
        }

        if (str.length() == 1) {
            char ch = str.charAt(0);
            if (ch == '\r' || ch == '\n') {
                return EMPTY;
            }
            return str;
        }

        int lastIdx = str.length() - 1;
        char last = str.charAt(lastIdx);

        if (last == '\n') {
            if (str.charAt(lastIdx - 1) == '\r') {
                lastIdx--;
            }
        } else if (last != '\r') {
            lastIdx++;
        }
        return str.substring(0, lastIdx);
    }

    /**
     * <p>Removes <code>separator</code> from the end of
     * <code>str</code> if it's there, otherwise leave it alone.</p>
     *
     * <p>NOTE: This method changed in version 2.0.
     * It now more closely matches Perl chomp.
     * For the previous behavior, use {@link #substringBeforeLast(String, String)}.
     * This method uses {@link String#endsWith(String)}.</p>
     *
     * <pre>
     * chomp(null, *)         = null
     * chomp("", *)           = ""
     * chomp("foobar", "bar") = "foo"
     * chomp("foobar", "baz") = "foobar"
     * chomp("foo", "foo")    = ""
     * chomp("foo ", "foo")   = "foo "
     * chomp(" foo", "foo")   = " "
     * chomp("foo", "foooo")  = "foo"
     * chomp("foo", "")       = "foo"
     * chomp("foo", null)     = "foo"
     * </pre>
     *
     * @param str  the String to chomp from, may be null
     * @param separator  separator String, may be null
     * @return String without trailing separator, <code>null</code> if null String input
     */
    public static String chomp(String str, String separator) {
        if (isEmpty(str) || separator == null) {
            return str;
        }
        if (str.endsWith(separator)) {
            return str.substring(0, str.length() - separator.length());
        }
        return str;
    }

    /**
     * <p>Checks if a String 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>
     *
     * <p>NOTE: This method changed in Lang version 2.0.
     * It no longer trims the String.
     * That functionality is available in isBlank().</p>
     *
     * @param str  the String to check, may be null
     * @return <code>true</code> if the String is empty or null
     */
    public static boolean isEmpty(String str) {
        return str == null || str.length() == 0;
    }

    /**
     * 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();
    }

    /**
     * <p>Gets a substring from the specified String avoiding exceptions.</p>
     *
     * <p>A negative start position can be used to start <code>n</code>
     * characters from the end of the String.</p>
     *
     * <p>A <code>null</code> String will return <code>null</code>.
     * An empty ("") String will return "".</p>
     *
     * <pre>
     * substring(null, *)   = null
     * substring("", *)     = ""
     * substring("abc", 0)  = "abc"
     * substring("abc", 2)  = "c"
     * substring("abc", 4)  = ""
     * substring("abc", -2) = "bc"
     * substring("abc", -4) = "abc"
     * </pre>
     *
     * @param str  the String to get the substring from, may be null
     * @param start  the position to start from, negative means
     *  count back from the end of the String by this many characters
     * @return substring from start position, <code>null</code> if null String input
     */
    public static String substring(String str, int start) {
        if (str == null) {
            return null;
        }

        // handle negatives, which means last n characters
        if (start < 0) {
            start = str.length() + start; // remember start is negative
        }

        if (start < 0) {
            start = 0;
        }
        if (start > str.length()) {
            return EMPTY;
        }

        return str.substring(start);
    }

    /**
     * <p>Gets a substring from the specified String avoiding exceptions.</p>
     *
     * <p>A negative start position can be used to start/end <code>n</code>
     * characters from the end of the String.</p>
     *
     * <p>The returned substring starts with the character in the <code>start</code>
     * position and ends before the <code>end</code> position. All position counting is
     * zero-based -- i.e., to start at the beginning of the string use
     * <code>start = 0</code>. Negative start and end positions can be used to
     * specify offsets relative to the end of the String.</p>
     *
     * <p>If <code>start</code> is not strictly to the left of <code>end</code>, ""
     * is returned.</p>
     *
     * <pre>
     * substring(null, *, *)    = null
     * substring("", * ,  *)    = "";
     * substring("abc", 0, 2)   = "ab"
     * substring("abc", 2, 0)   = ""
     * substring("abc", 2, 4)   = "c"
     * substring("abc", 4, 6)   = ""
     * substring("abc", 2, 2)   = ""
     * substring("abc", -2, -1) = "b"
     * substring("abc", -4, 2)  = "ab"
     * </pre>
     *
     * @param str  the String to get the substring from, may be null
     * @param start  the position to start from, negative means
     *  count back from the end of the String by this many characters
     * @param end  the position to end at (exclusive), negative means
     *  count back from the end of the String by this many characters
     * @return substring from start position to end positon,
     *  <code>null</code> if null String input
     */
    public static String substring(String str, int start, int end) {
        if (str == null) {
            return null;
        }

        // handle negatives
        if (end < 0) {
            end = str.length() + end; // remember end is negative
        }
        if (start < 0) {
            start = str.length() + start; // remember start is negative
        }

        // check length next
        if (end > str.length()) {
            end = str.length();
        }

        // if start is greater than end, return ""
        if (start > end) {
            return EMPTY;
        }

        if (start < 0) {
            start = 0;
        }
        if (end < 0) {
            end = 0;
        }

        return str.substring(start, end);
    }

    /**
     * <p>Check if a String ends with a specified suffix.</p>
     *
     * <p><code>null</code>s are handled without exceptions. Two <code>null</code>
     * references are considered to be equal. The comparison is case sensitive.</p>
     *
     * <pre>
     * endsWith(null, null)      = true
     * endsWith(null, "def")     = false
     * endsWith("abcdef", null)  = false
     * endsWith("abcdef", "def") = true
     * endsWith("ABCDEF", "def") = false
     * endsWith("ABCDEF", "cde") = false
     * </pre>
     *
     * @see java.lang.String#endsWith(String)
     * @param str  the String to check, may be null
     * @param suffix the suffix to find, may be null
     * @return <code>true</code> if the String ends with the suffix, case sensitive, or
     *  both <code>null</code>
     * @since 2.4
     */
    public static boolean endsWith(String str, String suffix) {
        return endsWith(str, suffix, false);
    }

    /**
     * <p>Check if a String ends with a specified suffix (optionally case insensitive).</p>
     *
     * @see java.lang.String#endsWith(String)
     * @param str  the String to check, may be null
     * @param suffix the suffix to find, may be null
     * @param ignoreCase inidicates whether the compare should ignore case
     *  (case insensitive) or not.
     * @return <code>true</code> if the String starts with the prefix or
     *  both <code>null</code>
     */
    private static boolean endsWith(String str, String suffix,
            boolean ignoreCase) {
        if (str == null || suffix == null) {
            return (str == null && suffix == null);
        }
        if (suffix.length() > str.length()) {
            return false;
        }
        int strOffset = str.length() - suffix.length();
        return str.regionMatches(ignoreCase, strOffset, suffix, 0,
                suffix.length());
    }
}

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