How to call the value of a variable?

How can I call the value of a variable of a function, into another function?

I'm using jPanel , where I'm going to add text with:

 jTextArea.append("AREA = " + /*AQUI*/);

Where it says HERE I wanted to put the value of a variable that I have in another class:

 public int setCoordenadasB(int x1, int y1, int x2, int y2) {
    p.x = Math.min(x1, x2);
    p.y = Math.min(y1, y2);
    largura = Math.abs(x1-x2);
    altura = Math.abs(y1-y2);
    area = largura * altura;
    return area;
}

It was this "area" that I liked to put in HERE up there.

r = new Retangulo();