split_and_replace.java

public class UpperCaseTest {
    public static void main (String[] args) {
        // toUpperCaseTest
        String stunum = "";
        String upperStunum = stunum.toUpperCase();
        System.out.println(upperStunum);

        // toLowerCaseTest
        String myName = "";
        String lowerStunum = myName.toLowerCase();
        System.out.println(lowerStunum);

        // splitTest
        String splitTest = "";

        String[] strArr = splitTest.split(",");
        for (String str : strArr) {
            System.out.println(str);
        }

        // join
        String[] strArr2 = splitTest.split(",");
        String joinTest = String.join(" ... ", strArr2);
        System.out.println(joinTest);
    }
}