User Input Random Numbers Then Program Sort Them In Different Ways - Missing Return Statement

I have been assigned to write a program that has a user input random numbers then the program is to sort them in different ways. I have the coding for the different sorts but, I have an error saying that I am missing a return statement in the "Bubble" method. I am trying to return "arr[i]" in the "for loop" which gives me this error, and when I try to take the "return arr[i]" outside of the "for()" loop the error reads the it cannot locate variable "i".

import java.awt.* ;
import java.awt.event.*;
import javax.swing.*;
public class SwingSorts extends JFrame implements ActionListener
{
JRadioButton bubble;
JRadioButton selection;

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