Here you can find the source of join(Object[] array, char separator, int startIndex, int endIndex)
Joins the elements of the provided array into a single String containing the provided list of elements.
No delimiter is added before or after the list.
| Parameter | Description |
|---|---|
| array | the array of values to join together, may be null |
| separator | the separator character to use |
| startIndex | the first index to start joining from. It is an error to pass in an end index past the end of the array |
| endIndex | the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array |
public static String join(Object[] array, char separator, int startIndex, int endIndex)
//package com.java2s; //License from project: Open Source License import java.util.Iterator; public class Main { /**//from ww w . jav a 2s. co m * The empty String {@code ""}. * @since 2.0 */ public static final String EMPTY = ""; /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No separator is added to the joined String. * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null) = null * StringUtils.join([]) = "" * StringUtils.join([null]) = "" * StringUtils.join(["a", "b", "c"]) = "abc" * StringUtils.join([null, "", "a"]) = "a" * </pre> * * @param <T> the specific type of values to join together * @param elements the values to join together, may be null * @return the joined String, {@code null} if null array input * @since 2.0 * @since 3.0 Changed signature to use varargs */ public static <T> String join(T... elements) { return join(elements, null); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], ';') = "a;b;c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join([null, "", "a"], ';') = ";;a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use * @return the joined String, {@code null} if null array input * @since 2.0 */ public static String join(Object[] array, char separator) { if (array == null) return null; return join(array, separator, 0, array.length); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], ';') = "a;b;c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join([null, "", "a"], ';') = ";;a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use * @param startIndex the first index to start joining from. It is * an error to pass in an end index past the end of the array * @param endIndex the index to stop joining from (exclusive). It is * an error to pass in an end index past the end of the array * @return the joined String, {@code null} if null array input * @since 2.0 */ public static String join(Object[] array, char separator, int startIndex, int endIndex) { if (array == null) return null; int noOfItems = endIndex - startIndex; if (noOfItems <= 0) return EMPTY; StringBuilder buf = new StringBuilder(noOfItems * 16); for (int i = startIndex; i < endIndex; i++) { if (i > startIndex) buf.append(separator); if (array[i] != null) buf.append(array[i]); } return buf.toString(); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String (""). * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], "--") = "a--b--c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join(["a", "b", "c"], "") = "abc" * StringUtils.join([null, "", "a"], ',') = ",,a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use, null treated as "" * @return the joined String, {@code null} if null array input */ public static String join(Object[] array, String separator) { if (array == null) return null; return join(array, separator, 0, array.length); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String (""). * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], "--") = "a--b--c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join(["a", "b", "c"], "") = "abc" * StringUtils.join([null, "", "a"], ',') = ",,a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use, null treated as "" * @param startIndex the first index to start joining from. It is * an error to pass in an end index past the end of the array * @param endIndex the index to stop joining from (exclusive). It is * an error to pass in an end index past the end of the array * @return the joined String, {@code null} if null array input */ public static String join(Object[] array, String separator, int startIndex, int endIndex) { if (array == null) return null; if (separator == null) separator = EMPTY; // endIndex - startIndex > 0: Len = NofStrings *(len(firstString) + len(separator)) // (Assuming that all Strings are roughly equally long) int noOfItems = endIndex - startIndex; if (noOfItems <= 0) return EMPTY; StringBuilder buf = new StringBuilder(noOfItems * 16); for (int i = startIndex; i < endIndex; i++) { if (i > startIndex) buf.append(separator); if (array[i] != null) buf.append(array[i]); } return buf.toString(); } /** * <p>Joins the elements of the provided {@code Iterator} into * a single String containing the provided elements.</p> * * <p>No delimiter is added before or after the list. Null objects or empty * strings within the iteration are represented by empty strings.</p> * * <p>See the examples here: {@link #join(Object[],char)}. </p> * * @param iterator the {@code Iterator} of values to join together, may be null * @param separator the separator character to use * @return the joined String, {@code null} if null iterator input * @since 2.0 */ public static String join(Iterator<?> iterator, char separator) { // handle null, zero and one elements before building a buffer if (iterator == null) return null; if (!iterator.hasNext()) return EMPTY; Object first = iterator.next(); if (!iterator.hasNext()) return first == null ? "" : first.toString(); // two or more elements StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small if (first != null) buf.append(first); while (iterator.hasNext()) { buf.append(separator); Object obj = iterator.next(); if (obj != null) buf.append(obj); } return buf.toString(); } /** * <p>Joins the elements of the provided {@code Iterator} into * a single String containing the provided elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String ("").</p> * * <p>See the examples here: {@link #join(Object[],String)}. </p> * * @param iterator the {@code Iterator} of values to join together, may be null * @param separator the separator character to use, null treated as "" * @return the joined String, {@code null} if null iterator input */ public static String join(Iterator<?> iterator, String separator) { // handle null, zero and one elements before building a buffer if (iterator == null) return null; if (!iterator.hasNext()) return EMPTY; Object first = iterator.next(); if (!iterator.hasNext()) return first == null ? "" : first.toString(); // two or more elements StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small if (first != null) buf.append(first); while (iterator.hasNext()) { if (separator != null) buf.append(separator); Object obj = iterator.next(); if (obj != null) buf.append(obj); } return buf.toString(); } /** * <p>Joins the elements of the provided {@code Iterable} into * a single String containing the provided elements.</p> * * <p>No delimiter is added before or after the list. Null objects or empty * strings within the iteration are represented by empty strings.</p> * * <p>See the examples here: {@link #join(Object[],char)}. </p> * * @param iterable the {@code Iterable} providing the values to join together, may be null * @param separator the separator character to use * @return the joined String, {@code null} if null iterator input * @since 2.3 */ public static String join(Iterable<?> iterable, char separator) { if (iterable == null) return null; return join(iterable.iterator(), separator); } /** * <p>Joins the elements of the provided {@code Iterable} into * a single String containing the provided elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String ("").</p> * * <p>See the examples here: {@link #join(Object[],String)}. </p> * * @param iterable the {@code Iterable} providing the values to join together, may be null * @param separator the separator character to use, null treated as "" * @return the joined String, {@code null} if null iterator input * @since 2.3 */ public static String join(Iterable<?> iterable, String separator) { if (iterable == null) return null; return join(iterable.iterator(), separator); } }