如何从字符串数组中随机获取项目？

Question

I am trying to generate random questions from my String array called Questions. There 10 items inside. I am trying to set the text of JLabel where once the button is click one of the questions from the array will randomly be selected and displayed. However these 2 sections of code doesn't return anyting.

public String getNextQuestion() {
    int NextQues = (int)(Math.random()*10);
    return Questions[NextQues];}

public void actionPerformed (ActionEvent e) {
     if(e.getSource() == Button) {  
Hello.setText(Questions[NextQues]);

Answer 1

Don't hardcode the magic number 10 in getNextQuestion() . I would prefer ThreadLocalRandom over Math.random() . Like,

public String getNextQuestion() {
    return Questions[ThreadLocalRandom.current().nextInt(Questions.length)];
}

Then invoke that method in actionPerformed like,

public void actionPerformed(ActionEvent e) {
    if (e.getSource() == Button) {
        Hello.setText(getNextQuestion());
    }
}

Answer 2

You should be calling your method getNextQuestion

OK, you need an actionlistener on your button in order for something to happen. Something like

    public String getNextQuestion() {
            int NextQues = (int)(Math.random()*10);
            return Questions[NextQues];}


// inside main method 
...    
    Button.addActionListener (
             new ActionListener()
             { 
                public void actionPerformed(ActionEvent e)
                {
                   Hello.setText(getNextQuestion());
                }
             });
 ...