How to implement MINIMAX algorithm for Checkers Game in Java?

Here's the code so far, required to add Minimax algorithm (function) below, just before the main class. I was trying to understand this pseudocode, so I can apply to my case. Unfortunately, I couldn't really understand.

``````function minimax(node, depth, maximizingPlayer) is
if depth = 0 or node is a terminal node then
return the heuristic value of node
if maximizingPlayer then
value := −∞
for each child of node do
value := max(value, minimax(child, depth − 1, FALSE))
return value
else (* minimizing player *)
value := +∞
for each child of node do
value := min(value, minimax(child, depth − 1, TRUE))
return value
``````
``````import java.awt.*;
import javax.swing.*;
import java.applet.*;
import java.net.*;

public class Checkers extends JFrame {

private static int [][] boardPlan = {
{0, 0, 0, 0, 0, 0, 0, 0},   //*** blue pieces become king here
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 1},
{1, 0, 4, 0, 3, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 2, 0, 0, 0}    //*** red pieces become king here
};

//*** the legend strings
private String[] legend = {"blank", "bs", "bk", "rs", "rk" };

//*** create the checkers board
private GameBoard board;

//*** the xy dimensions of each checkers cell on board
private int cellDimension;

//*** pause in seconds inbetween moves
private static int pauseDuration = 500;

Checkers() {
//*** set up the initial configuration of the board
board = new GameBoard(boardPlan);

//*** each board cell is 70 pixels long and wide
cellDimension = 70;

//*** set up the frame containign the board
getContentPane().setLayout(new GridLayout());
setSize(boardPlan.length * cellDimension, boardPlan.length * cellDimension);
setDefaultCloseOperation(EXIT_ON_CLOSE);

//*** enable viewer
setVisible(true);

//*** place all initial pieces on board and pause a bit
putInitialPieces();
pause(2 * pauseDuration);
}

public void pause(int milliseconds) {
try

catch (Exception e)
{}
}

void putPiece(int i, int j, String piece) {
//*** can do error checking here to make sure pieces are bs, bk, rs, rk
board.drawPiece(i, j, "images/" + piece + ".jpg");
}

void putInitialPieces() {
//*** use legend variables to draw one piece at a time
for (int i = 0; i < boardPlan.length; i++)
for (int j = 0; j < boardPlan.length; j++)
if (boardPlan[i][j] != 0)
{ board.drawPiece(i, j, "images/" + legend[boardPlan[i][j]] + ".jpg"); }
}

boolean legalPosition(int i) {
//*** can't go outside board boundaries
return ((i >= 0) && (i < boardPlan.length));
}

void movePiece(int i1, int j1, int i2, int j2, String piece) {
//*** raise exception if outside the board or moving into a non-empty
//*** cell
if ((boardPlan[i2][j2] != 0) || !legalPosition(i1) || !legalPosition(i2)
|| !legalPosition(j1) || !legalPosition(j1))
{ throw new IllegalMoveException("An illegal move was attempted."); }

//*** informative console messages
System.out.println("Moved " + piece + " from position [" +
i1 + ", " + j1 + "] to [" + i2 + ", " + j2 + "]");

//*** erase the old cell
board.drawPiece(i1, j1, "images/blank.jpg");

//*** draw the new cell
board.drawPiece(i2, j2, "images/" + piece + ".jpg");

//*** erase any captured piece from the board
if ((Math.abs(i1 - i2) == 2) && (Math.abs(j1 - j2) == 2)) {
//*** this handles  hops of length 2
//*** the captured piece is halfway in between the two moves
int captured_i = i1 + (i2 - i1) / 2;
int captured_j = j1 + (j2 - j1) / 2;

//*** now wait a bit
pause(pauseDuration);

//*** erase the captured cell
board.drawPiece(captured_i, captured_j, "images/blank.jpg");

//*** print which piece was captured
System.out.println("Captured " + legend[boardPlan[captured_i][captured_j]] +
" from position [" + captured_i + ", " + captured_j + "]");

//*** the captured piece is removed from the board with a bang
boardPlan[captured_i][captured_j] = 0;
Applet.newAudioClip(getClass().getResource("images/hit.wav")).play();
}

//*** update the internal representation of the board by moving the old
//*** piece into its new position and leaving a blank in its old position
boardPlan[i2][j2] = boardPlan[i1][j1];
boardPlan[i1][j1] = 0;

//*** red single is kinged
if ( (i2 == boardPlan.length - 1) && (boardPlan[i2][j2] == 3) ) {
boardPlan[i2][j2] = 4;
putPiece(i2, j2, "rk");
}

//*** blue single is kinged
if ( (i2 == 0) && (boardPlan[i2][j2] == 1) ) {
boardPlan[i2][j2] = 2;
putPiece(i2, j2, "bk");
}

//*** now wait a bit
pause(pauseDuration);
}

//*** incorporate your MINIMAX algorithm in here
//***********************************************************************
public static void main(String [] args) {
//*** create a new game and make it visible
Checkers game = new Checkers();

//*** arbitrarily move a few pieces around
//while (!game.done())
{
try {
//*** move a bs piece from board[4][7] to board[3][6]
game.movePiece(4, 7, 3, 6, "bs");

//*** move the rk from board[5][2] to board[4][1]
game.movePiece(5, 2, 4, 1, "rk");

//*** move a bs piece from board[5][0] to board[3][2]
//*** must capture rk in position board[4][1]
game.movePiece(5, 0, 3, 2, "bs");

//*** move the bk from board[7][4] to board[6]1]
game.movePiece(7, 4, 6, 3, "bk");

//*** move the rs from board[5][4] to board[7][2]
game.movePiece(5, 4, 7, 2, "rs");

//*** a few more moves just for fun
game.movePiece(3, 2, 2, 3, "bs");
game.movePiece(2, 3, 1, 4, "bs");
game.movePiece(1, 4, 0, 5, "bs");
game.movePiece(3, 6, 2, 5, "bs");
game.movePiece(2, 5, 1, 4, "bs");
game.movePiece(1, 4, 0, 3, "bs");

} catch (IllegalMoveException e)
{e.printStackTrace();}
}
}
}

``````

I've been trying for few days to search for the solution, but couldn't find the right one that associate with the code above. I would appreciate for your time and solution. Thanks!