How to clear TextField in an array?

Question

In my applet program I have the TextField declared in my public class header as:

TextField numbers [][] = new TextField[5][5];

I also have a button that is supposed to clear all the textboxes when clicked.

Right now I basically have this:

JButton b = new JButton("Clear");
b.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent e){
        numbers.setText("");
    }
});

But I'm getting an error: "Cannot invoke setText(null) on the array type TextField[][]"

How can I fix this?

Answer 1

Key lesson here: read the error message critically as it is telling you exactly what is wrong.

"Cannot invoke setText(null) on the array type TextField[][]"

You're treating the numbers variable as if it's a single TextField and it's not, and so you can't call setText(...) on it -- rather it's a 2D array of objects. A solution is to think of how you interact with any similar 2-d array, how do you call methods on each item held within the array: use nested for loops to iterate through the array.

for (int i = 0; i < numbers.length; i++) {
    for (int j = 0; j < numbers[i].length; j++) {
       numbers[i][j].setText("");
    }
}

Also, change TextField to JTextField so that you're using all Swing components:

// change type from TextField to JTextField
JTextField numbers [][] = new JTextField[5][5];