计算器中的 AWT 选择

Question

I basically don't know how to forward the value I get from a Choice and use it in a equation later on.

I'm building a calculator and I need to have a Choice control with operations and a button that calculates with the operation selected in the Choice.

b1 = Calculate button

This is the equation I use

Double n1 = Double.parseDouble(t1.getText());
Double n2 = Double.parseDouble(t2.getText());
     
 if (e.getSource() == b1) {
    t3.setText(String.valueOf(n1 [here should be the operator selected from the Choice] n2)); }

The idea is when clicked on the button Calculate n1 and n2 should perform operation selected in Choice control.

[ enter image description here ]( https://i.stack.imgur.com/9Dqwa.png )

Answer 1

Check the API documentation about Choice. That class offers the methods getSelectedItem() and getSelectedIndex() that you can use in your event listener.

Here is an example:

if (e.getSource() == b1) {
    switch(choice.getSelectedIndex()) {
        case 0:
            t3.setText(String.valueOf(n1 + n2));
            break; 
        case 1:
            t3.setText(String.valueOf(n1 - n2));
            break; 
        case 2:
            t3.setText(String.valueOf(n1 * n2));
            break; 
        case 3:
            t3.setText(String.valueOf(n1 / n2));
            break; 
    }
}