CODEWITHSUNDEEP
javaarrays
Ken
Ken

Reputation: 343

"For"-loop ceases to work properly (or I'm doing something wrong)

So the issue here is fairly simple; I have a "for"- loop that doesn't work properly. The "for"-loop is situated at the end of the second class, in the "generateBlock()" method. This "for"-loop is supposed to change the text of the labels from the array labels[] to "Text changed".

The problem I am encountering is that, if I set "for (i = 0; i < 12; i++);", I get an outofbounds error, and if I set "for (i = 0; i < 11; i++);", I don't have that outofbounds error. This is pretty strange since the index of the array actually consists of 0 to 11. But well, that is not even the main problem.

The main problem is that if I set "for (i = 0; i < 11; i++);", only the last labels[i] (thus labels[11]) has its text changed to "Text changed" while the other labels[i] all stay the same and thus unchanged.

This is pretty weird since i < 11 so labels[11] should be the only one to remain unchanged, but in this case it is apparently reversed and I don't know why. I also don't know why I get that outofbounds error if I set i < 12, since I'm pretty sure that the index of the array consists of 0 to 11.

If I manually set "coloredWords.labels[0].setText("Text changed");" and then copy paste this line for all the other values it does work though.

public class ColoredWordsExperiment {
    JFrame frame;
    JLabel[] labels;
    ButtonHandler buttonHandler;
    int i;

    ColoredWordsExperiment(){
        frame = new JFrame ();
        button1 = new JButton("Matching");

        labels = new JLabel[12];
        for (i = 0; i < 12; i++) {
            labels[i] = new JLabel("label");
            labelContainer.add(labels[i]);
        }

        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")) {
            generateBlock();
        }
    }

    public void generateBlock(){
        int i = 0;
        for (i = 0; i < 11; i++); {
            coloredWords.labels[i].setText("Text changed");
        }
    }

}

Upvotes: 0

Views: 64

Answers (2)

Moni
Moni

Reputation: 433

First your for loop is terminating as you are doing 

for( i = 0 ; i  < 11 ; i ++); // replace this line with

for( i =0; i <11; i++){

//your logic }

Second thing if you want to change your last label[11] change to "Text Changed", put tis condition inside the for loop -

If( i ==11){
    coloreWords.labels[i].set text("Text Changed");

} But you should just double check your array index,if it is really a 11 index array than your code should be run till i<12.

Upvotes: 1

Juned Ahsan
Juned Ahsan

Reputation: 68715

Your for loop is not executed even once because you have terminated it with a semicolon(;). Remove the semicolon after the for loop:

    for (i = 0; i < 11; i++); {

should be

    for (i = 0; i < 11; i++) {

Upvotes: 3

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