如何让用户只选择一个单选按钮？ 以及我如何为每个人定价并让用户支付他选择的门票？

Question

This is what ive done so far I tried the add the ButtonGroup but it keeps showing me that there is an error T_T

public class tram extends JFrame implements ActionListener, KeyListener {

TextArea output = new TextArea(6, 30);
JButton cancel = new JButton("Cancel");
JButton exit = new JButton("Exit");

JRadioButton Single = new JRadioButton("Single");
JRadioButton Double = new JRadioButton("Double");
JRadioButton ZoneA = new JRadioButton("Zone A");
JRadioButton ZoneA_B = new JRadioButton("Zone A&B");

I wrote the Button.Group here with changing the "new JRadioButton();" and it didnt work I am not sure if I should use if statement because I could not find a way to do it ^.^"

public tram(){

    JLabel title = new JLabel("Please select the type of ticket you wish to purchase");


        setLayout(new BorderLayout());
        setSize(450, 300);
        setTitle("Redwich Tram");

        JFrame frm = new JFrame();

        JPanel top = new JPanel();
        top.setBackground(Color.white);
        top.add(title);
        title.setFont(new Font("Courier", Font.BOLD, 12));
        add("North", top);

        JPanel middle = new JPanel(); 
        middle.setBackground(Color.WHITE);
        top.add(new JLabel("Select an option by clicking one of the buttons"));
        add("Center", middle); 
        middle.add(Single, BorderLayout.NORTH);
        Single.setBackground(Color.white);
        middle.add(Double, BorderLayout.CENTER);
        Double.setBackground(Color.white);
        middle.add(ZoneA, BorderLayout.SOUTH);
        ZoneA.setBackground(Color.white);
        middle.add(ZoneA_B, BorderLayout.SOUTH);
        ZoneA_B.setBackground(Color.white);


        middle.setBackground(Color.WHITE);
        middle.add(output);





        JPanel bottom = new JPanel();
        bottom.setBackground(Color.white);
        add("South", bottom);
        bottom.add(cancel,"South");
        cancel.setBackground(Color.white);
        bottom.add(exit,"South");
        exit.setBackground(Color.white);





        setResizable(false);
        setVisible(true);
    }

        public static void main(String[] args) {
        new tram();
    }

       public void onRadioButtonClicked(View view) {



       }




}

Answer 1

For JRadioButtons you have to add them to a ButtonGroup and set one of the buttons as selected.

Here is the Oracle tutorial .

Here's a small example:

JRadioButton b1 = new JRadioButton('option1);
b1.setSelected(true);

ButtonGroup g = new ButtonGroup();
g.add(b1);

Answer 2

As seen in the documentation of JRadioButton :

An implementation of a radio button -- an item that can be selected or deselected, and which displays its state to the user. Used with a ButtonGroup object to create a group of buttons in which only one button at a time can be selected. (Create a ButtonGroup object and use its add method to include the JRadioButton objects in the group

You must first create a ButtonGroup and add the JRadioButton in it

Answer 3

for this--How can I let the user choose only one radio button

see this it will help.
        ToggleGroup radioGroup=new ToggleGroup();
        option1radio.setToggleGroup(radioGroup);
        option2radio.setToggleGroup(radioGroup);
        option3radio.setToggleGroup(radioGroup);
        option4radio.setToggleGroup(radioGroup);

here option1,2,3,4radio are the radiobtn id's; Go through this it will help.