Java String Sub String substringAfter(String str, String separator)

Description

Gets the substring after the first occurrence of a separator.

License

Open Source License

Parameter

Parameter	Description
str	the String to get a substring from, may be null
separator	the String to search for, may be null

Return

the substring after the first occurrence of the separator, null if null String input

Declaration

public static String substringAfter(String str, String separator) 

Method Source Code

//package com.java2s;

public class Main {
    public static final String EMPTY = "";

    /**/*from  w  w  w. j  a v a2s.  c  o m*/
     * <p>Gets the substring after the first occurrence of a separator.
     * The separator is not returned.</p>
     *
     * <p>A <code>null</code> string input will return <code>null</code>.
     * An empty ("") string input will return the empty string.
     * A <code>null</code> separator will return the empty string if the
     * input string is not <code>null</code>.</p>
     *
     * <pre>
     * StringUtils.substringAfter(null, *)      = null
     * StringUtils.substringAfter("", *)        = ""
     * StringUtils.substringAfter(*, null)      = ""
     * StringUtils.substringAfter("abc", "a")   = "bc"
     * StringUtils.substringAfter("abcba", "b") = "cba"
     * StringUtils.substringAfter("abc", "c")   = ""
     * StringUtils.substringAfter("abc", "d")   = ""
     * StringUtils.substringAfter("abc", "")    = "abc"
     * </pre>
     *
     * @param str  the String to get a substring from, may be null
     * @param separator  the String to search for, may be null
     * @return the substring after the first occurrence of the separator,
     *  <code>null</code> if null String input
     */
    public static String substringAfter(String str, String separator) {
        if (isEmpty(str)) {
            return str;
        }
        if (separator == null) {
            return EMPTY;
        }
        int pos = str.indexOf(separator);
        if (pos == -1) {
            return EMPTY;
        }
        return str.substring(pos + separator.length());
    }

    /**
     * <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>
     *
     * @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;
    }

    /**
     * <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>
     * StringUtils.substring(null, *)   = null
     * StringUtils.substring("", *)     = ""
     * StringUtils.substring("abc", 0)  = "abc"
     * StringUtils.substring("abc", 2)  = "c"
     * StringUtils.substring("abc", 4)  = ""
     * StringUtils.substring("abc", -2) = "bc"
     * StringUtils.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>
     * StringUtils.substring(null, *, *)    = null
     * StringUtils.substring("", * ,  *)    = "";
     * StringUtils.substring("abc", 0, 2)   = "ab"
     * StringUtils.substring("abc", 2, 0)   = ""
     * StringUtils.substring("abc", 2, 4)   = "c"
     * StringUtils.substring("abc", 4, 6)   = ""
     * StringUtils.substring("abc", 2, 2)   = ""
     * StringUtils.substring("abc", -2, -1) = "b"
     * StringUtils.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);
    }
}

Related

1. substringAfter(String s, String substr, boolean fromend)
2. substringAfter(String sourceStr, String expr)
3. substringAfter(String str, int beginChar, boolean last)
4. substringAfter(String str, String delimiter)
5. substringAfter(String str, String separator)
6. substringAfter(String str, String separator)
7. substringAfter(String string, String delim)
8. substringAfter(String string, String delimiter)
9. substringAfter(String template, String toFind, String defaultTo)