How to use "return"?

[Chackan]

Hey there. Currently very new to Java, took classes but the teacher could be better so...trying to train and learn with some self-study!

Anyway, I have a Switch with several options. What I want is to return to the initial menu if a wrong option is given!

Example:

public class MenuPrincipal {


public static void main(String[] args) {

System.out.println("Menu");
System.out.println("Choose an option:");
System.out.println("1-First option");
System.out.println("2-Second option");
System.out.println("0-Exit");

Scanner s = new Scanner(System.in);
int opcao = s.nextInt();

switch ( opcao ) {
case 1:
System.out.println("Option 1");
break;
case 2:
System.out.println("Option 2");
break;
case 0:
System.out.println("Goodbye");
System.exit(2);
default:
System.out.println("Invalid Option. ");
return;

I want to return to the bolded part!

[Norm]

The return statement is for exiting the currently executing method. I think what you want to do is to loop back to an earlier section of code within a method. If you put the code you want to repeat inside a loop, then at any point inside that loop you can "return" to the beginning of the loop by using the continue statement.

[Chackan]

Ahhh ok! So the return statement is only used to exit the executing code, with some sort of answer, is that it?

By loop, do you mean while, if, etc?

[Norm]

return exits the currently executing method (possibly with a value) returning to the caller of the method.

for and while are two kinds of loops. The if statement is not a loop

[cselic]

Anyway, I have a Switch with several options. What I want is to return to the initial menu if a wrong option is given!

I'll give you a little clue just to get idea how it could be done. For example:

public static void main(String[] args) {

int opcao = 0;

while(!(opcao == 0)) {

// your code here

opcao = s.nextInt();

// your code here
}

}

[Norm]

@cselic Did you test your code? How many times will the code inside the while() loop execute?

[cselic]

^You're right, my previous code is not good. Here is the better one:

public static void main(String[] args) {
 
int opcao = -1;
 
while(!(opcao == 0)) {
 
// your code here
 
opcao = s.nextInt();
 
// your code here
}
 
}

[Norm]

while(!(opcao == 0)) {
Why use both ! and ==
why not just use != and make it clearer and easier to understand?
while(opcao != 0) {

[cselic]

^Norm you're right. That's much better.

public static void main(String[] args) {
  
int opcao = -1;
  
while((opcao != 0)) {
  
// your code here
  
opcao = s.nextInt();
  
// your code here
}
  
}

[Chackan]

Ok, I created the loop! Now I just need to make the loop return to the beggining of the menu! Will try searching for it, if I don't find anything, I will bug you guys a bit more :P

Thanks mates!