Static variable in Java not initializing

Question

So I am having trouble with the following code.

public class bw {
    public static int checked[][];
    public static BufferedImage input;

    public static void floodfill(int j, int i, int color, int spotColor, int th) throws Exception {
       input.setRGB(j, i, color);
    }

    public static void main(String args[]) throws Exception {
        BufferedImage input = ImageIO.read(new File("C:\\Users\\Aditya\\Desktop\\Lena.png"));       
        checked = new int[input.getHeight()][input.getWidth()];
        floodfill(250, 310, 0, input.getRGB(250,310), 35);
    }
}

Have taken out most of the irrelevant part from the code. The checked variable which is static is working fine. But the input variable which I have intialized in the main function is still null. It gived me null pointer exception from floodfill.

Answer 1

You have a local variable with the same name, inside main method as a local variable and as a static attribute . Therefore your static attribute is not get initialized instead of the local variable getting initialized

Answer 2

Try this

public class bw{
    public static int checked[][];
    public static BufferedImage input;

    public static void floodfill(int j, int i, int color, int spotColor, int th) throws Exception{
        input.setRGB(j, i, color);

    }
    public static void main(String args[]) throws Exception{
        input = ImageIO.read(new File("C:\\Users\\Aditya\\Desktop\\Lena.png"));       
        checked = new int[input.getHeight()][input.getWidth()];
        floodfill(250, 310, 0, input.getRGB(250,310), 35);

    }
}

You have declared variable input twice, so the input variable inside main method is initialized and the other(the static attribute) is not