Prompting User for Selection of Choice Again

Question

Hi, i am now a student learning through some basics of the java, i would like to know, say i have the following code;
choice = CspInput.readInt();
switch(choice)
case 1: System.out.println("www");
break;
case 2: System.out.println("xxx");
break;
case 3: System.out.println("yyy");
break;
case 4: System.out.println("zzz");
break;
default: System.out.println("wrong choice");
break;
how do i command the programme to prompt the user to enter again if he/she enter a invalid code rather than ending the programme with "Process Complete"
please help me with it,thanks!

Answer 1

i have alter the code such that it looks like this, but the output i want is such that i only want it to loop when the user enters a value that is less than 1,more than 4,how do i go about altering the code such that it does the job?
public static void main(String args[])
throws java.io.IOException {
int choice;
for(;;) {
do {
System.out.println("***************x,y or z?***************");
System.out.println("1) z");
System.out.println("2) y");
System.out.println("3) x");
System.out.println("4) Exit Program");
System.out.println("************************************************");
System.out.print("Please Select Your Choice (1-4) : ");
do {
choice = (int) System.in.read();
} while(choice == '\n' | choice == '\r');
} while( choice < '1' | choice > '3' & choice != '4');
if(choice == '4') break;
System.out.println("\n");
switch(choice) {
     case '1':
System.out.println("zzz");
break;
     case '2':
System.out.println("yyy");
break;
     case '3':
System.out.println("xxx");
break;
System.out.println();
}