Doubt easy program with a class and cicle for

Question

im creating a class which target is.... i set a sentence and a key that encrypt that sentence. It depends os de characters of key : example->1234, i ve to create a switch with the four cases and character by character it must change the sentence.
cases
1- takeRight ex: michael, change to-> lmichae
2- takeLeft ex: michael, change to ->ichaelm
3- takeRightText ex: i am michael, change to-> michael i am
4- takeLeftText ex: i am michael, change to->am michael i
How do i do cases 1and 3...? I know that cicle for is a good option...as the creation of String:
private String text;
private Int key;
public Int encrypt() {
switch (text) {
     case 1:
          for ( ; ; ) //i dont know//
          break;
     case 2:
          break;
     case 3:
          break;
     case 4:
          break;

Answer 1

but how do i put the code, i read and i didnt
understand...Which one did you not understand? What did you not understand? Which one are you trying to use?
Please be specific.