Need help in Android Studio

Question

I am new to learning Android and am learning from Udemy.

The lecture which I am currently learning is not explained clearly and I would like some help. In this lecture, the instructor is teaching to create a game called connect 3 which is similar to Tic Tac Toe. I have multiple issues with this lecture.

Issue 1: To initialize two players, the instructor first made an integer with value o at the start. The code is

int activePlayer = 0

The logic for the player was written as :

if (activePlayer == 0) {
    // change background image as red(This is not the real code);
    activePlayer = 1;
}

I am unable to understand, if the integer was taken initially at a fixed value, how can it be changed to another without any calculation?

Issue 2: Next the instructor is showing us a way of managing the game state, ie initially clicking two times would change the connect 3 boxes from yellow to red and vice versa. The instructor stops this by taking an array of integers:

int [] gameState = {2, 2, 2, 2, 2, 2, 2, 2, 2};

After creating the arrays, the instructor assigned tags (android: tag) to all the 9 imageViews used in the game layout. The tag was converted to a string and assigned an integer value. The tags were named as int tappedCounter .

This is where it gets weird:

The instructor then wrote an if command comparing the tag with gameState. The code is :

if (gameState[tappedCounter] == 2 {
    gameState[tappedCounter] = activePlayer;

    if (activePlayer == 0) {
        // change background image as red(This is not the real code);
        activePlayer = 1;
    } else {
        //set backgroung image to blue;
        activePlayer = 0;
}

Can anyone explain these things a little bit more clearly?

Answer 1

I am unable to understand, if the integer was taken initially at a fixed value, how can it be changed to another without any calculation.

You can assign different values to int variables, regardless if it is a result of calculation or constant.

It seems like the code

if(activePlayer==0){
   activePlayer = 1;} 

just switches the turn, ie if current turn was done by player 1 then switch to player 2, if turn was done by player 2 - switch to player one.

if( gameState[tappedCounter] == 2){
    gameState[tappedCounter] = activePlayer;
    if(activePlayer==0){
         activePlayer = 1;}
    else{
        activePlayer =0;
    }
}

The array of states describes state of each cell in the game. Seems like 2 - is state of empty cell. 0 - state of cell marked by player one ; 1 - state of cell marked of player 2. So this code does following - on each selection of cell:

• checks if cell is empty (state == 2)
• marks cell with marker of current player(0 or 1)
• switches player (0 to 1 and vice versa)