displaying values from HashMap

[Debra]

import javax.swing.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.color.*;
import javax.swing.border.*;
  
public class Test extends JFrame{
  
    private JRadioButton red, blue;
    private JLabel display;
    private HashMap<String, String> map = new HashMap<>();
  
    public static void main(String[] args){
  
        Test frame = new Test();
        frame.setTitle("Colors");
        frame.setSize(700, 300);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
  
  
    }
  
    public Test(){
  
        JPanel p1 = new JPanel();
        p1.setLayout(new GridLayout(1,5));
        p1.add(red = new JRadioButton("Red"));
        p1.add(blue = new JRadioButton("Blue"));
  
        add(p1, BorderLayout.NORTH);
        p1.setBorder(new TitledBorder("Group 1"));
  
  
  
        ButtonGroup group = new ButtonGroup();
        group.add(red);
        group.add(blue);
  
  
  
       map.put("Red", "FF0000");
       map.put("Blue", "0000FF");
  
        red.addActionListener(new ActionListener(){
  
            @Override
            public void actionPerformed(ActionEvent e) {
  
  
                getContentPane().setBackground(Color.red);
                display.setText("The hexadecimal for red is #" + map.get("Red"));
  
            }
    });
}

The program changes the background color but does not display the hexadecimal.

[DarrylBurke]

We haven't a clue about the context of that code. To get better help sooner, post a SSCCE (Short, Self Contained, Compilable and Executable) example that demonstrates the problem.

db

[Debra]

import javax.swing.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.color.*;
import javax.swing.border.*;
 
public class Test extends JFrame{
 
    private JRadioButton red, blue;
    private JLabel display;
    private HashMap<String, String> map = new HashMap<>();
 
    public static void main(String[] args){
 
        Test frame = new Test();
        frame.setTitle("Colors");
        frame.setSize(700, 300);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
 
 
    }
 
    public Test(){
 
        JPanel p1 = new JPanel();
        p1.setLayout(new GridLayout(1,5));
        p1.add(red = new JRadioButton("Red"));
        p1.add(blue = new JRadioButton("Blue"));
 
        add(p1, BorderLayout.NORTH);
        p1.setBorder(new TitledBorder("Group 1"));
 
 
 
        ButtonGroup group = new ButtonGroup();
        group.add(red);
        group.add(blue);
 
 
 
       map.put("Red", "FF0000");
       map.put("Blue", "0000FF");
 
        red.addActionListener(new ActionListener(){
 
            @Override
            public void actionPerformed(ActionEvent e) {
 
 
                getContentPane().setBackground(Color.red);
                display.setText("The hexadecimal for red is #" + map.get("Red"));
 
            }
    });
}

The program changes the background color but does not display the hexadecimal.

[quad64bit]

I agree with Daryl, buti think you want something like:

map.get("Red");

Also, it only needs to be static if the map is declared and to be used in a static context, that is if the containing class isn't being instantiated.

[wsaryada]

Actually your code produce a java.lang.NullPointerException exception because the display JLabel was never instantiated in your code.

[DarrylBurke]

Debra, please don't edit your posts after there are responses (except maybe to correct a spelling mistake), as that takes a response out of context and makes the thread difficult to follow.

db

[DarrylBurke]

Also learn that Swing constructors and methods, with very few exceptions, must be invoked on the EDT and not on the Main thread.
Lesson: Concurrency in Swing (The Java™ Tutorials > Creating a GUI With JFC/Swing)

db