Sorting and displaying a TreeMap by Increasing value Issues

Question

I am working on a TreeMap with an iterator that reads a text file with 20 name and hexadecimal values for example RED; FF0000. First in the main I made an Iterator but I am not sure why its not reading all 20 and displaying. Also trying to sort them in increasing value when I display them to the console.

Console Display:

`00008B=Dark Blue
013220=Dark Green
37FDFC=Blue
7f7f00=Dark Yellow
8B0000=Dark Red
B26200=Dark Orange
D3D3D3=Grey
FF0000=Red
FFC0CB=Pink
FFFFCC=Light Yellow`

Code:

public class coloring extends JFrame implements ActionListener {

public static TreeMap<String, String> buttonColors;

// Constructor
public FP(TreeMap<String, String> buttonColors) throws IOException {

    super("Hexidecimal Button Map");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setLocationRelativeTo(null);
    this.buttonColors = buttonColors;

    setSize(500, 400);
    setLayout(new FlowLayout());
    ButtonGroup buttonGroup = new ButtonGroup();

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

        JRadioButton button = new JRadioButton(coloringButtons.getValue()
                + "  " + coloringButtons.getKey());

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

        buttonGroup.add(button);
        add(button);
    }
}

public void actionPerformed(ActionEvent e) {

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

}

public static void main(String[] args) throws IOException {

    TreeMap<String, String> buttonColors = new TreeMap<String, String>();

    BufferedReader br = new BufferedReader(new FileReader("Input File.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();

        buttonColors.put(colorValue, colorName);
    }

    br.close();

    Set<Map.Entry<String, String>> buttons = buttonColors.entrySet();
    Iterator sortingItr = buttons.iterator();

    while (sortingItr.hasNext()) {

        Map.Entry<String, String> entry = (Map.Entry) sortingItr.next();
        System.out.println(sortingItr.next());

    }

    FP obj = new FP(buttonColors);
    obj.setVisible(true);
    obj.setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10));
}
}

Answer 1

See your code here:

Set<Map.Entry<String, String>> buttons = buttonColors.entrySet();
Iterator sortingItr = buttons.iterator();
while (sortingItr.hasNext()) {
    Map.Entry<String, String> entry = (Map.Entry) sortingItr.next();
                                                  ^^^^^^^^^^^^^^^^^
    System.out.println(sortingItr.next());
                       ^^^^^^^^^^^^^^^^^^
}

See that you are calling next method twice.

So you are advancing the cursor of iterator by calling next method on iterator two times and hence you see n/2 map elements in your output. You could just print map entry instead like:

System.out.println(entry);