Returning moves with MiniMax

Returning moves with MiniMax - java

I've got my code working and the program running perfectly! Turns out the problem also involved the computer not returning a 0 when required. Thank you to everyone who helped. If anyone needs any help like I did check out the code below.
import java.util.Scanner;
public class TicTacToeSolver{
public static void main(String[] args){
Scanner input=new Scanner(System.in);
char[] board={0,0,0,0,0,0,0,0,0};
int player=1,move;
System.out.println("Tic-Tac-Toe:");
while (true){
PrintBoard(board);
if (player==1){
System.out.print("Enter move: ");
move=input.nextInt();
if (ValidMove(board,move)==true){
board[move-1]='X';
player=-1;
}
}
else{
board[MiniMax(board,player,0,9)[1]]='O';
player=1;
}
if(CheckWin(board)!=0){
PrintBoard(board);
System.out.println("You lost!");
System.exit(0);
}
else if (CheckDraw(board)==true){
PrintBoard(board);
System.out.println("Draw!");
System.exit(0);
}
}
}
public static boolean ValidMove(char[]board,int move){
if(move>=1 && move<=9){
if (board[move-1]==0){
return true;
}
}
return false;
}
public static int CheckWin(char[] board){
if (board[0]=='X' && board[1]=='X' && board[2]=='X'||//Horizontal.
board[3]=='X' && board[4]=='X' && board[5]=='X' ||
board[6]=='X' && board[7]=='X' && board[8]=='X' ||
board[0]=='X' && board[4]=='X' && board[8]=='X' ||//Diagonal.
board[2]=='X' && board[4]=='X' && board[6]=='X' ||
board[0]=='X' && board[3]=='X' && board[6]=='X' ||//Vertical.
board[1]=='X' && board[4]=='X' && board[7]=='X' ||
board[2]=='X' && board[5]=='X' && board[8]=='X'){
return -1;
}
else if (board[0]=='O' && board[1]=='O' && board[2]=='O'||//Horizontal.
board[3]=='O' && board[4]=='O' && board[5]=='O' ||
board[6]=='O' && board[7]=='O' && board[8]=='O' ||
board[0]=='O' && board[4]=='O' && board[8]=='O' ||//Diagonal.
board[2]=='O' && board[4]=='O' && board[6]=='O' ||
board[0]=='O' && board[3]=='O' && board[6]=='O' ||//Vertical.
board[1]=='O' && board[4]=='O' && board[7]=='O' ||
board[2]=='O' && board[5]=='O' && board[8]=='O'){
return 1;
}
return 0;
}
public static boolean CheckDraw(char[] board){
int total=0;
for (int i=0;i<9;i++){
if (board[i]!=0){
total+=1;
}
}
if (total==9){
return true;
}
return false;
}
public static void PrintBoard(char[] board){
System.out.println("------------------------------");
System.out.println(board[0]+"|"+board[1]+"|"+board[2]);
System.out.println("-+-+-");
System.out.println(board[3]+"|"+board[4]+"|"+board[5]);
System.out.println("-+-+-");
System.out.println(board[6]+"|"+board[7]+"|"+board[8]);
System.out.println("\n");
}
public static int[] MiniMax(char[] board,int player,int depth, int maxDepth){
int bestScore,bestMove=-1,score;
if (CheckWin(board)!=0||depth==maxDepth){
return new int[] {CheckWin(board),bestMove};
}
if (CheckDraw(board)==true){
return new int[] {0,bestMove};
}
if (player==-1){
bestScore=-9999;
}
else{
bestScore=9999;
}
for (int i=0;i<9;i++){
if (board[i]==0){
if (player==-1){
board[i]='O';
score=MiniMax(board,player*-1,depth+1,maxDepth)[0];
board[i]=0;
if (score>bestScore){
bestScore=score;
bestMove=i;
}
}
else{
board[i]='X';
score=MiniMax(board,player*-1,depth+1,maxDepth)[0];
board[i]=0;
if(score<bestScore){
bestScore=score;
bestMove=i;
}
}
}
}
return new int[] {bestScore,bestMove};
}
}

I think I've answered this elsewhere so there must be a few of you doing this assignment! Below the first level you should only be checking if the levels below return any winning moves or not. You don't need to use any of their values. Example code:
public List<Location> bestMoves() {
List<Location> winningMoves = possibleMoves().stream()
.filter(move -> apply(move).isWinFor(nextPlayer))
.collect(Collectors.toList());
if (!winningMoves.isEmpty())
return winningMoves;
else
return possibleMoves().stream()
.filter(move -> apply(move).bestMoves().isEmpty())
.collect(Collectors.toList());
}

You could return both the move and the score through an object that contains both.
public class TicTacToeSolver{
private static class Move {
int move;
int score;
Move( int m, int s ) {
move = m;
score = s;
}
}
...
}
You could return this object like this:
return new Move( bestScore, bestMove );
Within minimax() itself, you could get the score like this:
Move candidateMove = MiniMax(board,player*-1,depth+1,maxDepth);
int score = candidateMove.score;
At the top level, you could get the best move like this:
Move bestMove = MiniMax(board,player,0,9);
int move = bestMove.move;

Related

Peg solitaire solution change destination

I wrote a program that solves a peg solitaire in java.
My program gets a starting board and a destination board and try to finish the game.
I have a sort of counter that count my turn because I have a destination with more the 1 peg rest and as assume that if I have to remove only 2 pegs so I can solve it in only 2 moves.
I have an board class that I create:
public class Board {
private int board[][] = new int[7][7];
public Board(String place)
{
board[0][0]=2;
board[1][0]=2;
board[5][0]=2;
board[6][0]=2;
board[0][1]=2;
board[1][1]=2;
board[5][1]=2;
board[6][1]=2;
board[0][5]=2;
board[1][5]=2;
board[5][5]=2;
board[6][5]=2;
board[0][6]=2;
board[1][6]=2;
board[5][6]=2;
board[6][6]=2;
int loca=0;//location on the string of place
for(int i=0;i<7;i++){
for(int j=0;j<7;j++){
if(board[i][j]!=2) {
if (place.charAt(loca) == 'O') {
loca++;
board[i][j] = 1;
} else if (place.charAt(loca) == '.') {
loca++;
board[i][j] = 0;
}
}
System.out.print(board[i][j]);//print for test
}
System.out.println();//print for test
}
System.out.println();
}
public Board(Board copy){
for(int i=0;i<7;i++)
{
for(int j=0;j<7;j++)
{
board[i][j]=copy.getValue(i,j);
}
}
}
public int getValue(int x, int y)
{
return board[x][y];
}
public boolean isFinished(Board destination)
{
for(int i=0;i<7;i++)
{
for(int j=0;j<7;j++)
{
if(this.getValue(i,j)!=destination.getValue(i,j))
{
return false;
}
}
}
return true;
}
public Board turn(Board board,String direction,int x,int y)
{
if(direction.equals("right"))
{
board.setValue(x,y,0);
board.setValue(x+1,y,0);
board.setValue(x+2,y,1);
return board;
}
else if(direction.equals("left"))
{
board.setValue(x,y,0);
board.setValue(x-1,y,0);
board.setValue(x-2,y,1);
return board;
}
else if(direction.equals("up"))
{
board.setValue(x,y,0);
board.setValue(x,y-1,0);
board.setValue(x,y-2,1);
return board;
}
else if(direction.equals("down"))
{
board.setValue(x,y,0);
board.setValue(x,y+1,0);
board.setValue(x,y+2,1);
return board;
}
else{
System.out.println("there is not such direction, method turn on board class");
return null;//just for caution
}
}
public boolean isLegal(int x, int y){
if(board[x][y]==2)
{
return false;
}
else{
return true;
}
}
public boolean canTurn(String direction,int x,int y){
if(direction.equals("right"))
{
if(x<5) {
if (board[x][y] == 1 && board[x + 1][y] == 1 && board[x + 2][y] == 0) {
return true;
}
}
}
else if(direction.equals("left"))
{
if(x>1) {
if (board[x][y] == 1 && board[x - 1][y] == 1 && board[x - 2][y] == 0) {
return true;
}
}
}
else if(direction.equals("up"))
{
if(y>1) {
if (board[x][y] == 1 && board[x][y - 1] == 1 && board[x][y - 2] == 0) {
return true;
}
}
}
else if(direction.equals("down"))
{
if(y<5) {
if (board[x][y] == 1 && board[x][y + 1] == 1 && board[x][y + 2] == 0) {
return true;
}
}
}
else{
System.out.println("there is not such direction, method canTurn on board class");
return false;//just for caution
}
return false;
}
public void setValue(int x, int y, int value)
{
board[x][y]=value;
}
}
and I wrote my "solver" class.
public class PegSolver {
public int peg =1;
Board destinationBoard = new Board("OOOOOOOOOOOOOOOOO..OOOOOOOOOOOOOO");
Board board = new Board("OOOOOOOOOOOOOOOO.OOOOOOOOOOOOOOOO");
public void start(){
solve(0,board);
}
public boolean solve(int turn, Board board){
Board temp = new Board(board);
if(turn>peg)
{
return false;
}
else if(turn==peg){
//todo:check if solve
if(temp.isFinished(destinationBoard))
{
System.out.println("solution");
return true;
}
else
{
return false;
}
}
else//lower then 8
{
for(int i=0;i<7;i++){
for (int j=0;j<7;j++)
{
if(board.isLegal(i,j)) {
if(board.canTurn("right",i,j) && solve(turn++, temp.turn(temp, "right", i, j)))
{
return true;
}
else if(board.canTurn("left",i,j) && solve(turn++, temp.turn(temp, "left", i, j)))
{
return true;
}
else if(board.canTurn("up",i,j) && solve(turn++, temp.turn(temp, "up", i, j)))
{
return true;
}
else if(board.canTurn("down",i,j) && solve(turn++, temp.turn(temp, "down", i, j)))
{
return true;
}
}
}
}
}
return false;
}
}
When the program finds a solution, it needs to print "solution" but for some reason my program can't find a solution even when it's a basic destination with one move.
Can someone help me please?

Please review the modified code.
Many of the changes are related to indices and directions inconsistency across the code: where x represents horizontal index and y represents vertical index: array index should be board[y][x] (and not board[x][y]).
Many "magic numbers" were changed to constants for better readability of the code.
A toString method was added to the Boardclass to print out a board state. It uses special characters to make a nice printout :
This is helpful when debugging.
public class PegSolver {
private final Board startBoard, destinationBoard;
public PegSolver(Board startBoard, Board destinationBoard) {
super();
this.startBoard = startBoard;
this.destinationBoard = destinationBoard;
}
public void start(){
solve(0,startBoard);
}
private boolean solve(int turn, Board board){
//check if solve
if(board.isFinished(destinationBoard))
{
System.out.println("solved after "+ turn +" turns");
return true;
}
for(int x=0;x<board.boardSize();x++){
for (int y=0;y<board.boardSize();y++)
{
if(board.isLegal(x,y)) {
if(board.canTurn("right",x,y)
//turn++ changed to turn+1 so turn is incremented before invoking next solve
//and avoid changing the value of turn
&& solve(turn+1, board.turn(new Board(board), "right", x, y)))
return true;
else if(board.canTurn("left",x,y)
&& solve(turn+1, board.turn(new Board(board), "left", x, y)))
return true;
else if(board.canTurn("up",x,y)
&& solve(turn+1, board.turn(new Board(board), "up", x, y)))
return true;
else if(board.canTurn("down",x,y)
&& solve(turn+1, board.turn(new Board(board), "down", x, y)))
return true;
}
}
}
return false;
}
public static void main(String[] args) {
Board[] destinationBoards = {
//by order of number of turns
new Board("OOOOOOOOOOOOOO..OOOOOOOOOOOOOOOOO"), //one right turn
new Board("OOO.OOOO.OOOOO.OOOOOOOOOOOOOOOOOO"), //right, down
new Board("OOO.OO..OOOOOO.OOOOOOOOOOOOOOOOOO"), //right, down,right
new Board("OOO.OOO.OOOOO..OOOOO.OOOOOOOOOOOO"), //right, down,right,up
new Board("OOOOOOO..OOOO...OOOO.OOOOOOOOOOOO"), //right, down,right,up,up
new Board(".OO.OOO.OOOOO...OOOO.OOOOOOOOOOOO"), //right, down,right,up,up,down
new Board(".OO.OOO.OOOOO...OOOOO..OOOOOOOOOO"), //right, down,right,up,up,down, left
new Board(".OO.OOO.OOOOO...OOOOO.OOOOO.OO.OO"), //right, down,right,up,up,down,left,up
new Board(".OO.OO..O.OOO...OOOOO.OOOOO.OO.OO"), //10 turns
new Board("..O..O.O..OOO...OOOO..OOOOO..O..O"), //15 turns
new Board(".........O................O......"), //30 turns
new Board("...................O............."), //31 turns
};
Board startBoard = new Board("OOOOOOOOOOOOOOOO.OOOOOOOOOOOOOOOO");
for(Board destinationBoard : destinationBoards ){
new PegSolver(startBoard, destinationBoard).start();
}
}
}
class Board {
//int representation of the three states of a board cell
private final static int EMPTY = 0, PEG = 1, BORDER = 2;
/*cahr representation of the three states of a board cell
special chars are used to get nice printout
todo: change board to char[][] to avoid the need for two
representations (int and char)
*/
private final static char[] CHAR_REPRESENTATION = {9898,9899,10062};
private final static char ERROR = '?';
private final int BOARD_SIZE=7, CORNER_SIZE=2;
private final int board[][] = new int[BOARD_SIZE][BOARD_SIZE];
public Board(String place) {
int loca=0;
for(int y=0;y<BOARD_SIZE;y++){
for(int x=0;x<BOARD_SIZE;x++){
if(isWithinBoard(x,y)) {
if (place.charAt(loca) == 'O') {
loca++;
board[y][x] = PEG;
} else if (place.charAt(loca) == '.') {
loca++;
board[y][x] = EMPTY;
}
}else{
board[y][x] = BORDER;
}
}
}
//for testing
//System.out.println(this);
}
//copy constructor
public Board(Board copy){
for(int x=0;x<BOARD_SIZE;x++)
{
for(int y=0;y<BOARD_SIZE;y++)
{
board[y][x]=copy.getValue(x,y);
}
}
}
public int getValue(int x, int y)
{
return board[y][x]; //and not return board[x][y];
}
public boolean isFinished(Board destination)
{
for(int i=0;i<BOARD_SIZE;i++)
{
for(int j=0;j<BOARD_SIZE;j++)
{
if(this.getValue(i,j)!=destination.getValue(i,j))
return false;
}
}
return true;
}
public Board turn(Board board,String direction,int x,int y)
{
if(direction.equals("right"))
{
board.setValue(x,y,EMPTY);
board.setValue(x+1,y,EMPTY);
board.setValue(x+2,y,PEG);
return board;
}
else if(direction.equals("left"))
{
board.setValue(x,y,EMPTY);
board.setValue(x-1,y,EMPTY);
board.setValue(x-2,y,PEG);
return board;
}
else if(direction.equals("up"))
{
board.setValue(x,y,EMPTY);
board.setValue(x,y-1,EMPTY);
board.setValue(x,y-2,PEG);
return board;
}
else if(direction.equals("down"))
{
board.setValue(x,y,EMPTY);
board.setValue(x,y+1,EMPTY);
board.setValue(x,y+2,PEG);
return board;
}
System.out.println("there is not such direction, method turn on startBoard class");
return null;
}
public boolean isLegal(int x, int y){
if(board[y][x]==BORDER) //and not if(board[x][y]==BORDER)
return false;
return true;
}
public boolean canTurn(String direction,int x,int y){
if(direction.equals("right") && x < BOARD_SIZE - 2)
{
if (board[y][x] == PEG && board[y][x + 1] == PEG && board[y][x + 2] == EMPTY)
return true;
}
else if(direction.equals("left") && x > 1)
{
if (board[y][x] == PEG && board[y][x - 1] == PEG && board[y][x - 2] == EMPTY)
return true;
}
else if(direction.equals("up") && y > 1)
{
if (board[y][x] == PEG && board[y - 1][x] == PEG && board[y - 2][x] == EMPTY)
return true;
}
else if(direction.equals("down") && y < BOARD_SIZE - 2)
{
if (board[y][x] == PEG && board[y + 1][x] == PEG && board[y + 2][x] == EMPTY)
return true;
}
return false;
}
public void setValue(int x, int y, int value)
{
board[y][x]=value; //and not board[x][y]=value;
}
//for square nxn board
public int boardSize(){
return board.length;
}
public boolean isWithinBoard(int x, int y){
//check bounds
if (x < 0 || y < 0 || x >= BOARD_SIZE || y >= BOARD_SIZE) return false;
//left top corner
if (x < CORNER_SIZE && y < CORNER_SIZE) return false;
//right top corner
if(x >= BOARD_SIZE - CORNER_SIZE && y < CORNER_SIZE) return false;
//left bottom corner
if(x < CORNER_SIZE && y >= BOARD_SIZE - CORNER_SIZE) return false;
//right bottom corner
if(x >= BOARD_SIZE - CORNER_SIZE && y >= BOARD_SIZE - CORNER_SIZE) return false;
return true;
}
#Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (int[] row : board) {
for(int cell : row){
if(cell<CHAR_REPRESENTATION.length && cell >= 0) {
sb.append(CHAR_REPRESENTATION[cell]);
}else{
sb.append(ERROR);
}
}
sb.append("\n"); //new line
}
return sb.toString();
}
}
Todo:
The code is working but it needs further in-depth testing and debugging.
If something is not clear, don't hesitate to ask.

Getting Compilation error : "java:9: error: ';' expected";

I'm getting this compilation error:
Solution.java:9: error: ';' expected
boolean isEVen(){
^
Code:
import java.util.Scanner;
public class Solution {
public static void main (String[] args){
Scanner s = new Scanner(System.in);
int n = s.nextInt();
boolean isEVen(){
return n%2==0;
}
if (isEVen() && n<=5 && n>=2){
System.out.println("Not Weird");
}else{
if(!isEVen()){
System.out.println("Weird");
}else{
if(isEVen() && n>=6 && n<=20){
System.out.println("Weird");
} else{
if (isEVen() && n>20){
System.out.println("Not Weird");
}
}
}
}
}
}
Where am I supposed to put the semi-colon?

Update your code as below.
Move isEVen() method outside of main method and pass int n as a parameter to it.
import java.util.Scanner;
public class Solution {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
int n = s.nextInt();
if (isEVen(n) && n <= 5 && n >= 2) {
System.out.println("Not Weird");
} else {
if (!isEVen(n)) {
System.out.println("Weird");
} else {
if (isEVen(n) && n >= 6 && n <= 20) {
System.out.println("Weird");
} else {
if (isEVen(n) && n > 20) {
System.out.println("Not Weird");
}
}
}
}
}
static boolean isEVen(int n) {
return n % 2 == 0;
}
}

Another approach is to move all the processing outside of main method and into the Solution class itself:
import java.util.Scanner;
public class Solution
{
protected boolean isEVen(int n)
{
return n % 2 == 0;
}
protected void doSomething()
{
Scanner s = new Scanner(System.in);
int n = s.nextInt();
if (isEVen(n) && n <= 5 && n >= 2)
{
System.out.println("Not Weird");
}
else
{
if (!isEVen(n))
{
System.out.println("Weird");
}
else
{
if (isEVen(n) && n >= 6 && n <= 20)
{
System.out.println("Weird");
}
else
{
if (isEVen(n) && n > 20)
{
System.out.println("Not Weird");
}
}
}
}
}
public static void main(String[] args)
{
Solution s = new Solution();
s.doSomething();
}
}

Java Program: return statements not working

This program creates various methods for a class and runs each method. When I run the methods, the return statements do not work in the methods, although the integer value entered is definitely passed to the object (I tested with a print statement). I am sure the issue is somewhere with my static declarations.
can anyone help?
import java.util.Scanner;
public class MyInteger {
public static int storedValue;
public int value;
public static void main(String[] args){
Scanner input = new Scanner(System.in);
System.out.println("Class with various methods test. Please enter an integer:");
int num = input.nextInt();
MyInteger x = new MyInteger(num);
storedValue = x.value;
System.out.println("Now performing returnInt");
x.returnInt();
System.out.println("Now performing isEven");
x.isEven();
}
MyInteger(int a){
value = a;
}
public int returnInt(){
return storedValue;
}
public boolean isEven(){
if(value % 2 == 0){
return true;
}
else{
return false;
}
}
public boolean isOdd(){
if(value % 2 != 0){
return true;
}
else{
return false;
}
}
public boolean isPrime(){
if (value == 2){
return true;
}
for (int i = 2; i < value;i++){
if (value % i == 0){
return false;
}
}
return true;
}
public boolean isEven(int a){
if (a % 2 == 0){
return true;
}
else{
return false;
}
}
public boolean isOdd(int a){
if (a % 2 != 0){
return true;
}
else{
return false;
}
}
public boolean isPrime(int a){
if (a == 2){
return true;
}
for (int i = 2; i < a;i++){
if (a % i == 0){
return false;
}
}
return true;
}
public boolean isEven(MyInteger a){
if (a.value % 2 == 0){
return true;
}
else{
return false;
}
}
public boolean isOdd(MyInteger a){
if (a.value % 2 != 0){
return true;
}
else{
return false;
}
}
public boolean isPrime(MyInteger a){
if (a.value == 2){
return true;
}
for (int i = 2; i < a.value;i++){
if (a.value % i == 0){
return false;
}
}
return true;
}
public boolean equals(int a){
if (value == a){
return true;
}
else{
return false;
}
}
public boolean equals(MyInteger a){
if (value == a.value){
return true;
}
else{
return false;
}
}
public int parseInt(String s, int radix){
for (int i = (s.length()-1); i >= 0; i--){
radix += (int)s.charAt(i)*(Math.pow(10, i));
}
return radix;
}
}

First, remove the static storedvalue.
// public static int storedValue;
Then change your returnInt to return the value. Like,
public int returnInt(){
return value;
}
Finally, assign the return(ed) value in your caller (main, or use it directly). Something like
System.out.println("Now performing returnInt");
int v = x.returnInt();
System.out.printf("Value = %d%n", v);
System.out.println("Now performing isEven");
if (x.isEven()) {
System.out.println("It's even");
} else {
System.out.println("It's odd");
}

Simple Java Method Error when Returning

I'm learning methods and was trying to write code that basically tells if a number is prime. However, I keep encountering the error:
error: cannot find symbol
return(isPrime);
^
error: illegal start of type
return(isPrime);
This is my current code (i hope i'm using the method correctly):
import java.util.Scanner;
public class DoublePalindromicPrimes{
public static void main(String args[]){
Scanner in= new Scanner(System.in);
System.out.println("Please enter a number:");
int n = in.nextInt();
//prime(n);
boolean resultPrime = prime(n);
if (resultPrime){
System.out.println("This is a prime");
}
else {
System.out.println("This is not a prime");
}
}
public static boolean prime(int x){
for (int i=2;i<x;i++){
boolean isPrime;
if (x%i==0){
isPrime=false;
}
else{
isPrime=true;
}
}
return isPrime;
}
}
Any help is appreciated!

public static boolean isPrime(int x)
{
if(x > 2) {
if(x%2 == 0) {
return false;
} else {
int sqrt = (int)(Math.sqrt(x));
for(int i=3;i<=sqrt;i+=2) {
if(x%i == 0) {
return false;
}
}
}
return true;
} else if(x==2) {
return true;
} else { //1, 0, and negatives
return false;
}
}

change it to
return isPrime;
note the space and make declaration out of isPrime for loop

You declared isPrime inside your loop, so the return statement can't see it. Move it outside the loop.

public static boolean prime(int x) //throws InvalidNumberException
{
if (x <= 0)
{
//throw new InvalidNumberException("The number is invalid");
}
int squareRoot = (int)(Math.sqrt(x));
for (int i = 2; i <= squareRoot; i++)
{
if (x % i == 0)
{
return false;
}
}
return true;
}
This is an optimized prime validator.

2 returns firing in the same function?

Well been working for hours today so i might be missing something silly, but, at this point I'm kinda blind with this and looking for an explanation for this behaviour
i made an example of the problem I'm having and the solution i found is not quite a solution.
The Problem: to the following function I pass 1 as shotCount and 9 as Countdown
the result when i debug, i see the first if run, and run the return 2, but then also the else decides to run to and finally return -1
public int getNextShot(int shotCount, int Countdown)
{
if ((shotCount == 1) && (Countdown != 10)) return 2;
else if (shotCount == 0) return 1;
else return -1;
}
BUT if i do this (same parameters) it works:
public int getNextShot(int shotCount, int Countdown)
{
int res = -2;
if ((shotCount == 1) && (Countdown != 10)) res = 2;
else if (shotCount == 0) res = 1;
else res = -1;
return res;
}
Am I missing something here?
Thanks :)

I think you are mistaken.
Sometimes the debugger in Eclipse acts like its jumping to the last line of the method call but then does return the correct value.
For example, I just copied and pasted your code and it ran fine for me. The below code prints 2.
public class AA {
public static void main(String[] args) {
System.out.println(getNextShot(1, 9));
}
public static int getNextShot(int shotCount, int Countdown)
{
if ((shotCount == 1) && (Countdown != 10)) return 2;
else if (shotCount == 0) return 1;
else return -1;
}
}

This code is OK. When I run this:
public static int getNextShot1(int shotCount, int Countdown) {
if ((shotCount == 1) && (Countdown != 10)) {
return 2;
} else if (shotCount == 0) {
return 1;
} else {
return -1;
}
}
public static int getNextShot2(int shotCount, int Countdown) {
int res = -2;
if ((shotCount == 1) && !(Countdown == 10)) {
res = 2;
} else if (shotCount == 0) {
res = 1;
} else {
res = -1;
}
return res;
}
public static void main(String[] args) throws KeyStoreException, ParseException {
System.out.println(getNextShot1(1, 9));
System.out.println(getNextShot2(1, 9));
}
I get
2
2
on console :)
Second function could look like this (final keyword):
public static int getNextShot2(int shotCount, int Countdown) {
final int res;
if ((shotCount == 1) && !(Countdown == 10)) {
res = 2;
} else if (shotCount == 0) {
res = 1;
} else {
res = -1;
}
return res;
}

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

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