public void getUserInput() {
        line1x1 = JOptionPane.showInputDialog(this, "Input a starting x value for line 1 (1-600)");
        int x1 = Integer.parseInt(line1x1);
        if (!(x1>=1 && x1<=600)){
        JOptionPane.showMessageDialog(this, "Value out of range. Please enter a value between 1 & 600.");
        line1x1 = JOptionPane.showInputDialog(this, "Input a starting x value for line 1 (1-600)");}

        line1y1 = JOptionPane.showInputDialog(this, "Input a starting y value for line 1 (1-600)");
        int y1 = Integer.parseInt(line1y1);
        if (!(y1>=1 && y1<=600)){
        JOptionPane.showMessageDialog(this, "Value out of range. Please enter a value between 1 & 600.");
        line1y1 = JOptionPane.showInputDialog(this, "Input a starting y value for line 1 (1-600)");}