Check out example codes for "java flood fill". It will help you in understanding the concepts better.

Code Example 1

// Java program to implement flood fill algorithm 
class GFG 
{ 
  
// Dimentions of paint screen 
static int M = 8; 
static int N = 8; 
  
// A recursive function to replace previous color 'prevC' at '(x, y)'  
// and all surrounding pixels of (x, y) with new color 'newC' and 
static void floodFillUtil(int screen[][], int x, int y,  
                                    int prevC, int newC) 
{ 
    // Base cases 
    if (x < 0 || x >= M || y < 0 || y >= N) 
        return; 
    if (screen[x][y] != prevC) 
        return; 
  
    // Replace the color at (x, y) 
    screen[x][y] = newC; 
  
    // Recur for north, east, south and west 
    floodFillUtil(screen, x+1, y, prevC, newC); 
    floodFillUtil(screen, x-1, y, prevC, newC); 
    floodFillUtil(screen, x, y+1, prevC, newC); 
    floodFillUtil(screen, x, y-1, prevC, newC); 
} 
  
// It mainly finds the previous color on (x, y) and 
// calls floodFillUtil() 
static void floodFill(int screen[][], int x, int y, int newC) 
{ 
    int prevC = screen[x][y]; 
    floodFillUtil(screen, x, y, prevC, newC); 
} 
  
public static void main(String[] args)  
{ 
    int screen[][] = {{1, 1, 1, 1, 1, 1, 1, 1}, 
                    {1, 1, 1, 1, 1, 1, 0, 0}, 
                    {1, 0, 0, 1, 1, 0, 1, 1}, 
                    {1, 2, 2, 2, 2, 0, 1, 0}, 
                    {1, 1, 1, 2, 2, 0, 1, 0}, 
                    {1, 1, 1, 2, 2, 2, 2, 0}, 
                    {1, 1, 1, 1, 1, 2, 1, 1}, 
                    {1, 1, 1, 1, 1, 2, 2, 1}, 
                    }; 
    int x = 4, y = 4, newC = 3; 
    floodFill(screen, x, y, newC); 
  
    System.out.println("Updated screen after call to floodFill: "); 
    for (int i = 0; i < M; i++) 
    { 
        for (int j = 0; j < N; j++) 
        System.out.print(screen[i][j] + " "); 
        System.out.println(); 
    } 
    } 
}

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