( IM USING NETBEANS FOR JAVA GUI )

I have 2 Jframe. Mainmenu and Purchase.
In the Mainmenu Jframe, i have put a button and named it “Continue”. (with some other things, ofc)
Inside the “Continue Button” i used this code:

        Purchase purchase = new Purchase();
        //--------------Toyota---------------
        if(InputTinnova.isSelected())
        {
            String mobil = "Toyota Innova";
            Purchase.Onamamobil.setText(mobil);
        }
        if(InputTavanza.isSelected())
        {
            String mobil = "Toyota Avanza";
        }
        if(InputTalphard.isSelected())
        {
            String mobil = "Toyota Alphard";
        }
        if(InputTsupra.isSelected())
        {
            String mobil = "Toyota Supra";
        }
        
        //--------------NISSAN---------------
        if(InputNlivina.isSelected())
        {
            String mobil = "Nissan Livina";
        }
        if(InputNserena.isSelected())
        {
            String mobil = "Nissan Serena";
        }
        if(InputNterra.isSelected())
        {
            String mobil = "Nissan Terra";
        }
        if(InputNgtr.isSelected())
        {
            String mobil = "Nissan GTR";
        }
        
        //--------------Mazda---------------
        if(InputMcx.isSelected())
        {
            String mobil = "Mazda CX";
        }
        if(InputMmx.isSelected())
        {
            String mobil = "Mazda MX";
        }
        if(InputM3.isSelected())
        {
            String mobil = "Mazda 3";
        }
        if(InputMrx.isSelected())
        {
            String mobil = "Mazda RX";
        }
        
        
        
        
        purchase.show();
        dispose();

the variable Onamamobil is the Jlabel i want to change, but it keeps giving me an error saying “Non static variable Onamamobil cannot be referenced from a static content”. i made the Onamamobil a public Jlabel text, too.

I want the code from Mainmenu jframe

            String mobil = "Toyota Innova";
            Purchase.Onamamobil.setText(mobil);

changes the jlabel Onamamobil in the jframe Purchase.