Java数组不存储初始化时提供给它的数据

Question

I'm a newb to Java and am trying to test a small quiz app with NetBeans.

I'm using JRadioButtons and button groups for multiple choice questions, and I thought to use an array to store all of the correct answers, as seen below.

private final javax.swing.JRadioButton correctAnswers[]= 
    {radioButtonOption1Question1,radioButtonOption1Question2,
    radioButtonOption1Question3,radioButtonOption1Question4,
    radioButtonOption1Question5,radioButtonOption1Question6};

*Edit , this array is under the block of code Netbeans makes to initizialize all of the JFrame objects I have like the radiobuttons

However whenever I call on the array I get a null pointer exception error, and upon further investigation I found that the array was only storing 6 null values.

Why is this? Thanks

Also here's the loop sending the error when I run it

for(int i= 0;i<= 5;i++){
    if(correctAnswers[i].isSelected()){
    numCorrect++;
    }

    correctAnswers[i].setForeground(Color.green);
}

Answer 1

You are probably not initializing your radiobuttons anywhere. Keep in mind that if you want to store them as final variables, you HAVE to do it immediately:

private final radioButtonOption1Question1 = new JRadioButton( [your options here] )

or in the constructor of your class.

Answer 2

What you have done is the equivalent of...

JRadioButton radioButtonOption1Question1;

Java recognizes it but cant find it's initialization so you've got to initialize everyone of those RadioButtons individually.

radioButtonOption1Question1 = new JRadioButton(args[]);