Prerequisite: StringJoiner
StringJoiner is very useful, when you need to join Strings in a Stream.
Task : Suppose we want the string “[George:Sally:Fred]”, where we have given a string array that contains “George”, “Sally” and “Fred”.
StringJoiner provide add(String str) method to concatenate the strings based on supplied delimiter,prefix and suffix in the constructor, but if we use StringBuilder to perform our task then first we have to append prefix and then iterate through string array and append the required delimiter after each element and finally append the prefix. Below is the java program to demonstrate both ways.
Java
// Java program to demonstrate use of// StringJoiner class over StringBuilder classimport java.util.StringJoiner;public class Test{ public static void main(String[] args) { // given string array String str[] = {"George","Sally","Fred"}; // By using StringJoiner class // initializing StringJoiner instance with // required delimiter, prefix and suffix StringJoiner sj = new StringJoiner(":", "[", "]"); // concatenating strings sj.add("George").add("Sally").add("Fred"); // converting StringJoiner to String String desiredString = sj.toString(); System.out.println(desiredString); // By using StringBuilder class // declaring empty stringbuilder StringBuilder sb = new StringBuilder(); // appending prefix sb.append("["); // checking for empty string array if(str.length>0) { // appending first element sb.append(str[0]); // iterating through string array // and appending required delimiter for (int i = 1; i < str.length; i++) { sb.append(":").append(str[i]); } } // finally appending suffix sb.append("]"); // converting StringBuilder to String String desiredString1 = sb.toString(); System.out.println(desiredString1); }} |
Output:
[George:Sally:Fred] [George:Sally:Fred]
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