这种方法究竟发生了什么？

Question

I want to make a method which returns an array of buttons containing the letter of them . I wrote the method but I'm not sure what exactly happens?

public JButton [] button(){
    JButton [] button = null ;
    for(int i = 0 ;i<26 ;i++){
        String letter  = String.valueOf((char)(i + 'A'));
        button[i] = new JButton(letter);
    }
    return  button() ;
}

Answer 1

Create the array first as following

JButton [] button = new JButton[26];  // see null is removed.

and return properly

return button; // removed paranthesis

Answer 2

You are calling the method recursively and indefinitely:

return button() ;

That should be:

return button;

Best would be avoiding naming methods and variables confusingly. Also, you'll need to initialize the button array properly:

JButton[] button = new JButton[26];

Answer 3

You will get a NullPointerException because your array is not initialised:

JButton [] button = new JButton[26];

And at your return statement you call the method again which will cause an infinite loop.

return button; // removed paranthesis

This will return the array you create in the loop.

Your code should look like this:

public JButton [] button(){
    JButton [] button = new JButton[26];
    for(int i = 0 ;i<26 ;i++){
        String letter  = String.valueOf((char)(i + 'A'));
        buttons[i] = new JButton(letter);
    }
    return button;
}

To your question what the code does:

It creates an array of JButtons labeled with one letter from A to Z