if 语句、标签和组合框

Question

Ok my code has to pick route combo box (check) display in label(check) have a return and single ticket combobox(check) need it to display text(check) my problem is it only prints text related to one of my statments hope someone can tell me how to fix my if statments. The lable changes on a button .It reads code by lable.So far it only prints 15 and wont print 20 unless i had another label but this wouldnt make sense for the program

    package learning;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList.*;
import java.util.Arrays.*;
import java.util.List.*;


@SuppressWarnings("unused")
public class test {

    String[] items = {"Tipperary_to_cork","Cork_to_Dublin","Limerick_to_Tipperary","Dublin_to_Cork"};
    JComboBox c = new JComboBox(items);
    JButton b = new JButton("From");
    JLabel l = new JLabel();

    String[] items2 = {"window","aisle"};
    JComboBox m = new JComboBox(items2); 
    JButton  n = new JButton("Seat");
    JLabel  o = new JLabel();

    String[] items3 = {"Single","return"};
    JComboBox x = new JComboBox(items3); 
    JButton  y= new JButton("Ticket");
    JLabel  z = new JLabel("choose Ticket");

    String[] items4 = {"1","2","3","4","5","6","7","8","9","10"};
    JComboBox<?> xx = new JComboBox(items4); 
    JButton  yy = new JButton("seat");
    JLabel  zz = new JLabel("Choose a seat");
    JLabel  hh = new JLabel("cost");
    JButton  ccc = new JButton("comfirm");
    JLabel  hhh = new JLabel("");{

    }


    public test(){


    frame();

    }
     public void frame(){

    JFrame wolf = new JFrame();//frame
    wolf.setVisible(true);
    wolf.setSize(350,350);
    wolf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );

    JPanel p = new JPanel();


    p.add(hh);
    p.add(c);//
    p.add(b);//
    p.add(l);//lable1
    p.add(m);//
    p.add(n);//
    p.add(o);//lable 2
    p.add(x);//
    p.add(y);//
    p.add(z);//lable 2
    p.add(xx);//
    p.add(yy);//
    p.add(zz);//lable 2
    p.add(ccc);
    p.add(hhh);
    wolf.add(p);


    b.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
    String s = c.getSelectedItem().toString();
        l.setText(s);
        }
    });


     n.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
        String s = m.getSelectedItem().toString();
            o.setText(s);
            }
        });

     y.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
        String s = x.getSelectedItem().toString();
            z.setText(s);
            }
        });
     yy.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
        String s = xx.getSelectedItem().toString();
            zz.setText(s);
            }
        });
     }
     {

     if(l.getText().equals("Tipperary_to_cork")&&(z.getText().equals("single"))){
            ccc.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e){
                    hh.setText("15");                          //***

}});        
            if(l.getText().equals("Tipperary_to_cork")&&(z.getText().equals("return"))){
            ccc.addActionListener(new ActionListener(){      
                public void actionPerformed(ActionEvent e){
                    hh.setText("20");                          //****

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



    new test(); 
    }
}

Answer 1

You want to check "if some condition" when you click the button. So, start with one simple if statement inside one of the actionPerformed methods. You shouldn't add an action listener inside an if statement, you should always perform an action, and determine the event inside that action.

For example

b.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent e){
        String s = c.getSelectedItem().toString();
        if (s.equals("Tipperary to cork")) {
            // TODO: do something 
        }
    }
});

Original answer

These line just happen to work because you have if(false==false)

if(l.equals("Tipperary to cork")==(z.equals("single"))) { ... }
if(l.equals("Tipperary to cork")==(z.equals("return"))) { ... }

The reason they evaluate to false is because you are comparing a JLabel.equals(String) . You should use l.getText().equals("text here") , but...

The problem is that you have those if statements inside the constructor for your class, meaning that they are the first thing that is evaluated in your code. You should move the corrected if statements into the ActionListener s for the respective buttons.

Additional note: You seem to want "Tipperary to cork" AND "single" . In that case, use && in place of == . Alternatively, you could do this (psuedocode intentional)

if "Tipperary to cork" {
    if "single" { ... }
    else if "return" { ... }
}  

In reality, though, you should compare c.getSelectedItem().toString() instead of the text of the label, but that's your decision.