Java - Write code to Join all of the strings in arr into one String with separator added between each element.

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Requirements

Write code to Join all of the strings in arr into one String with separator added between each element.

Demo

//package com.book2s;

public class Main {
    public static void main(String[] argv) {
        String[] arr = new String[] { "1", "abc", "level", null,
                "book2s.com", "asdf 123" };
        String separator = "|";
        System.out.println(join(arr, separator));
    }//from  ww  w.  ja v  a 2s .  c o  m

    /**
     * Joins all of the strings in arr into one String with separator added
     * between each element.
     */
    public static String join(final String[] arr, final String separator) {
        if (arr.length < 2)
            return (arr.length == 1 ? arr[0] : "");
        final StringBuffer sb = new StringBuffer(arr[0]);
        for (int i = 1; i < arr.length; ++i) {
            sb.append(separator);
            sb.append(arr[i]);
        }
        return sb.toString();
    }
}

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