How do I break the while statement?(java)

Question

So this program asks for different areas of shapes, and it was requested that the user be able to control whether they want the program to continue or stop. I created an if statement, within the while loop that if the user entered "stop" the program would break. However, after testing the program is continuing to run. How do I break the while loop?

import java.util.Scanner;
public class assignmentu3b {
static int area;
static String stop;
    public static void main(String[]args) {
    Scanner sc=new Scanner(System.in);
    System.out.println("Would you like to find the area of a rectangle,circle or triangle");
    String inp=sc.next();
    inp.toLowerCase();
    while(true) {
        System.out.println("Enter stop, to leave the program, or anythinng else to continue, the program will run once.");
        stop=sc.next();
        stop.toLowerCase();
        if(stop=="stop") {
            break;
        }
    switch(inp) {
    case "circle":
        area=circle(area);
        System.out.println("The area of the circle is "+area);
        break;
    case "rectangle":
        area=rectangle(area, area);
        System.out.println("The area of the rectangle is "+area);
    break;
    case "triangle":
        area=triangle(area, area);
        System.out.println("The area of the triangle is "+area);
        break;
        default:
            System.out.println("You didn't enter a shape");
    }
    
}
}

public static int circle(int radius) {
    Scanner sc= new Scanner(System.in);
    System.out.println("Enter a radius:");
    radius=sc.nextInt();
    return (int) (Math.PI*Math.pow(radius,2));
    
}
public static int rectangle(int lenght,int width) {
    Scanner sc= new Scanner(System.in);
    System.out.println("Enter a lenght and width");
    lenght=sc.nextInt();
    width=sc.nextInt();
    return lenght*width;
}

public static int triangle(int base,int height) {
    Scanner sc= new Scanner(System.in);
    System.out.println("Enter a base and height");
    base=sc.nextInt();
    height=sc.nextInt();
    return (base*height)/2;
    
}

}