Java String Last Index Of lastIndexOf(String str, char searchChar)

Description

Finds the last index within a String, handling null.

License

Open Source License

Parameter

Parameter	Description
str	the String to check, may be null
searchChar	the character to find

Return

the last index of the search character, -1 if no match or null string input

Declaration

public static int lastIndexOf(String str, char searchChar) 

Method Source Code

//package com.java2s;

public class Main {
    /**//  w ww . jav a 2s.  c o m
     * <p>Finds the last index within a String, handling <code>null</code>.
     * This method uses {@link String#lastIndexOf(int)}.</p>
     *
     * <p>A <code>null</code> or empty ("") String will return <code>-1</code>.</p>
     *
     * <pre>
     * StringUtils.lastIndexOf(null, *)         = -1
     * StringUtils.lastIndexOf("", *)           = -1
     * StringUtils.lastIndexOf("aabaabaa", 'a') = 7
     * StringUtils.lastIndexOf("aabaabaa", 'b') = 5
     * </pre>
     *
     * @param str  the String to check, may be null
     * @param searchChar  the character to find
     * @return the last index of the search character,
     *  -1 if no match or <code>null</code> string input
     * @since 2.0
     */
    public static int lastIndexOf(String str, char searchChar) {
        if (isEmpty(str)) {
            return -1;
        }
        return str.lastIndexOf(searchChar);
    }

    /**
     * <p>Finds the last index within a String from a start position,
     * handling <code>null</code>.
     * This method uses {@link String#lastIndexOf(int, int)}.</p>
     *
     * <p>A <code>null</code> or empty ("") String will return <code>-1</code>.
     * A negative start position returns <code>-1</code>.
     * A start position greater than the string length searches the whole string.</p>
     *
     * <pre>
     * StringUtils.lastIndexOf(null, *, *)          = -1
     * StringUtils.lastIndexOf("", *,  *)           = -1
     * StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
     * StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
     * StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
     * StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
     * StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
     * StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0
     * </pre>
     *
     * @param str  the String to check, may be null
     * @param searchChar  the character to find
     * @param startPos  the start position
     * @return the last index of the search character,
     *  -1 if no match or <code>null</code> string input
     * @since 2.0
     */
    public static int lastIndexOf(String str, char searchChar, int startPos) {
        if (isEmpty(str)) {
            return -1;
        }
        return str.lastIndexOf(searchChar, startPos);
    }

    /**
     * <p>Finds the last index within a String, handling <code>null</code>.
     * This method uses {@link String#lastIndexOf(String)}.</p>
     *
     * <p>A <code>null</code> String will return <code>-1</code>.</p>
     *
     * <pre>
     * StringUtils.lastIndexOf(null, *)          = -1
     * StringUtils.lastIndexOf(*, null)          = -1
     * StringUtils.lastIndexOf("", "")           = 0
     * StringUtils.lastIndexOf("aabaabaa", "a")  = 0
     * StringUtils.lastIndexOf("aabaabaa", "b")  = 2
     * StringUtils.lastIndexOf("aabaabaa", "ab") = 1
     * StringUtils.lastIndexOf("aabaabaa", "")   = 8
     * </pre>
     *
     * @param str  the String to check, may be null
     * @param searchStr  the String to find, may be null
     * @return the last index of the search String,
     *  -1 if no match or <code>null</code> string input
     * @since 2.0
     */
    public static int lastIndexOf(String str, String searchStr) {
        if (str == null || searchStr == null) {
            return -1;
        }
        return str.lastIndexOf(searchStr);
    }

    /**
     * <p>Finds the first index within a String, handling <code>null</code>.
     * This method uses {@link String#lastIndexOf(String, int)}.</p>
     *
     * <p>A <code>null</code> String will return <code>-1</code>.
     * A negative start position returns <code>-1</code>.
     * An empty ("") search String always matches unless the start position is negative.
     * A start position greater than the string length searches the whole string.</p>
     *
     * <pre>
     * StringUtils.lastIndexOf(null, *, *)          = -1
     * StringUtils.lastIndexOf(*, null, *)          = -1
     * StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
     * StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
     * StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
     * StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
     * StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
     * StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
     * StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1
     * </pre>
     *
     * @param str  the String to check, may be null
     * @param searchStr  the String to find, may be null
     * @param startPos  the start position, negative treated as zero
     * @return the first index of the search String,
     *  -1 if no match or <code>null</code> string input
     * @since 2.0
     */
    public static int lastIndexOf(String str, String searchStr, int startPos) {
        if (str == null || searchStr == null) {
            return -1;
        }
        return str.lastIndexOf(searchStr, startPos);
    }

    /**
     * <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;
    }
}

Related

1. lastIndexOf(String input, char ch, int offset)
2. lastIndexOf(String path, char ch)
3. lastIndexOf(String s, String sub, int startIndex, int endIndex)
4. lastIndexOf(String self, String pattern, Integer start)
5. lastIndexOf(String str, char searchChar)
6. lastIndexOf(String str, String searchChar)
7. lastIndexOf(String str, String substr)
8. lastIndexOf(String string, char value, int startIndex, int count)
9. lastIndexOf(String string, char... chars)