Change the View

drawing and updating

1. The game will have 3 states: MENU, GAME, and END. These are repesented by final int variables that you must create in the GamePanel class. Their names are captialized since their values will not change:

    final int MENU = 0;
    final int GAME = 1;
    final int END = 2;

2. The game will keep track of which state it is in, via an int variable called currentState. Declare and initialize this variable as follows:

    int currentState = MENU;

3. Create 3 void methods for updating the game in each state:

 updateMenuState() {  }
 updateGameState() {  }
 updateEndState()  {  }

4. Create 3 void methods for drawing the game in each state. Note: these methods need a Graphics parameter because they will draw objects onto the panel's Graphics (like the paintComponent method).

 drawMenuState(Graphics g) {  }
 drawGameState(Graphics g) {  }
 drawEndState(Graphics g)  {  }

6. In the paintComponent() method, remove the code that draws a rectangle, and replace it with an if/else block that will check the currentState variable. Call the appropriate draw method inside the if/else block as shown.

if(currentState == MENU){
    drawMenuState(g);
}else if(currentState == GAME){
    drawGameState(g);
}else if(currentState == END){
    drawEndState(g);
}

Note: pass the Graphics object to each draw method.

7. In the drawMenuState() method, fill the game window with a blue rectangle using the following code:

g.setColor(Color.BLUE);
g.fillRect(0, 0, LeagueInvaders.WIDTH, LeagueInvaders.HEIGHT);

Similarly, fill the game window with black in the drawGameState() method and red in the drawEndState()method.

TESTING

8. Run the program. The game window should be filled by a blue rectangle.