为什么此类无法找到此数组？

Question

I have an array which works in the first class ( ColoredWordsExperiment ), while the second class, ( ButtonHandler ), cannot find it.

The strange thing is that if I, in the ButtonHandler class, substitute coloredWords.labels[i] or let's say "coloredWords.labels[1]" for simply coloredWords.labels1 , while in the first class I declare JLabel labels1 = new JLabel; it works.

That's basically what I initially had but since I have 12 labels I decided to use an array instead. The problem now is that the class ButtonHandler cannot find the variable "coloredWords.labels[i]".

This is the code (I left out unimportant stuff otherwise the code would be quite long):

public class ColoredWordsExperiment {
    ButtonHandler buttonHandler;

    ColoredWordsExperiment(){
        JLabel[] labels = new JLabel[12];
        for (i = 0; i < 12; i++) {
        labels[i] = new JLabel("Press Button");
        labels[i].setPreferredSize(new Dimension(90,40));
        labels[i].setOpaque(true);
        labels[i].setBackground(Color.white);
        labels[i].setHorizontalAlignment(SwingConstants.CENTER);
        labelContainer.add(labels[i]);
        }

    button1 = new JButton("Matching");
    buttonHandler = new ButtonHandler(this);
    button1.addActionListener(buttonHandler);
    }

    public static void main(String[] arg) {
        new ColoredWordsExperiment();
    }
}

-

class ButtonHandler implements ActionListener {
    ColoredWordsExperiment coloredWords;
    public ButtonHandler(ColoredWordsExperiment coloredWords) {
        this.coloredWords = coloredWords;
    }

    @Override
    public void actionPerformed(ActionEvent e){
    if (e.getActionCommand().equals("Matching")) {
        for (i = 0; i < 12; i++) {
            coloredWords.labels[i].setText("Text changed");
        }
    }
}

Answer 1

JLabel[] labels is a variable declared inside the constructor of your ColoredWordsExperiment class. Move this as a field in the class and initialize it in your class constructor:

public class ColoredWordsExperiment {
    ButtonHandler buttonHandler;
    //it should be declared here
    JLabel[] labels;

    ColoredWordsExperiment() {
        //this is a variable inside the class constructor
        //JLabel[] labels = new JLabel[12];
        //this line initializes the labels field
        labels = new JLabel[12];
        // rest of your code...
    }
}

Also, you should declare a getter method to obtain one of the JLabel s inside the labels variable instead of using a direct access to this variable. This will make your code cleaner.