Java Accessing Hexadecimal Text Files For HashMaping

Question

I am making a GUI were I have to make buttons and the background changes. The program is using a Java Collection Framework were I went with a Hashmap. I am really having trouble understanding and trying to do is access a txt file then read the pairs and store them in the hashmap. the txt file contains the pairs color - hexadecimal value on separate lines which will sort the pairs in the increasing order of their hexadecimal values and use iterators to display the sorted pairs to the console. I tried a BufferReader but got errors but I am guessing that is no the best way to use for a map.

//Input File.txt

Red FF0000

Blue 000084

Green 00FF00

Yellow FFFF00

Orange FF8C00

Pink FFC0CB

Grey D3D3D3

Brown 964B00

Purple 800080

Black 000000

Dark green 013220

Dark Red 8B0000

Dark blue 00008B

Dark Orange D97700

Dark grey 363737

Dark Purple 471E8A

Dark yellow 7f7f00

Light Yellow FFFFCC

Light Blue C0D9D9

Light Purple D8BFD8

Here is the code to get that I already started and finally got working for the GUI.

public class FP extends JFrame implements ActionListener {

BufferedReader reader = new BufferedReader(new FileReader(new File("Input File.txt")));
private Map<String, String> buttonColors;

// Constructor
public FP() {

    super("ColorMap");
    buttonColors = new HashMap<String, String>();

    //test button
    buttonColors.put("Red", "FF0000");

    setSize(400, 400);
    setLayout(new FlowLayout());
    ButtonGroup buttonGroup = new ButtonGroup();

    for (Map.Entry<String, String> coloringButtons : buttonColors
            .entrySet()) {

        JRadioButton button = new JRadioButton(coloringButtons.getKey());

        button.setActionCommand(coloringButtons.getValue());
        button.addActionListener(this);

        // Add this new color-button to the button group
        buttonGroup.add(button);
        add(button);
    }
}

@Override
public void actionPerformed(ActionEvent e) {

    String color = e.getActionCommand();
    getContentPane().setBackground(new Color(Integer.parseInt(color, 16)));

}

public static void main(String[] args) {

    FP obj = new FP();
    obj.setVisible(true);
}
}

Answer 1

here is your code modified to read the file and populate a HashMap, in this case I am using a TreeMap to sort the hex fields in order, see if this works for you,

public class FP extends JFrame implements ActionListener {

private TreeMap<String, String> buttonColors;

// Constructor
public FP() {

    super("ColorMap");
    buttonColors = new TreeMap<String, String>();

    BufferedReader br = new BufferedReader(new FileReader("InputFile.txt");
    while(true)
    {
      String str = br.readLine();
      if(str==null)break;
      if(str.length()==0)continue;
      string[] st = str.split(" ");
      string colorName = st[0].trim();
      string colorValue = st[1].trim();

      //* to have the colors sorted by the hex value
      buttonColors.put(colorValue, colorName);
    }
    br.close();

    //test button
    //buttonColors.put("Red", "FF0000");

    setSize(400, 400);
    setLayout(new FlowLayout());
    ButtonGroup buttonGroup = new ButtonGroup();

    for (Map.Entry<String, String> coloringButtons : buttonColors
            .entrySet()) {

        JRadioButton button = new JRadioButton(coloringButtons.getValue());

        button.setActionCommand(coloringButtons.getKey());
        button.addActionListener(this);

        // Add this new color-button to the button group
        buttonGroup.add(button);
        add(button);
    }
}