The correct diagram to use

Question

I would like to ask what is the correct UML diagram to use for this project of mine. This is an Android app. UML Diagrams:

• class diagram
• object diagram
• use case diagram
• sequence diagram
• collaboration diagram
• statechart diagram
• activity diagram
• component diagram
• deployment diagram

here is the android app code(it is a tictactoe game):

MainActivity.java

package com.example.sample;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;

public class MainActivity extends Activity {

    // Representing the game state:
    private boolean noughtsTurn = false; // Who's turn is it? false=X true=O
    private char board[][] = new char[3][3]; // for now we will represent the board as an array of characters

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setupOnClickListeners();
        resetButtons();


    }

    /**
     * Called when you press new game.
     *
     * @param view the New Game Button
     */
    public void newGame(View view) {

        noughtsTurn = false;
        board = new char[3][3];
        resetButtons();

    }

    /**
     * Reset each button in the grid to be blank and enabled.
     */
    private void resetButtons() {
        TableLayout T = (TableLayout) findViewById(R.id.tableLayout);
        for (int y = 0; y < T.getChildCount(); y++) {
            if (T.getChildAt(y) instanceof TableRow) {
                TableRow R = (TableRow) T.getChildAt(y);
                for (int x = 0; x < R.getChildCount(); x++) {
                    if (R.getChildAt(x) instanceof Button) {
                        Button B = (Button) R.getChildAt(x);
                        B.setText("");
                        B.setEnabled(true);
                    }
                }
            }
        }
        TextView t = (TextView) findViewById(R.id.TextView);
        t.setText(R.string.TextView);
    }

    /**
     * Method that returns true when someone has won and false when nobody has.<br />
     * It also display the winner on screen.
     *
     * @return
     */
    private boolean checkWin() {

        char winner = '\0';
        if (checkWinner(board, 3, 'X')) {
            winner = 'X';
        } else if (checkWinner(board, 3, 'O')) {
            winner = 'O';
        }

        if (winner == '\0') {
            return false; // nobody won
        } else {
            // display winner
            TextView T = (TextView) findViewById(R.id.TextView);
            T.setText(winner + " wins");
            return true;
        }
    }


    /**
     * This is a generic algorithm for checking if a specific player has won on a tic tac toe board of any size.
     *
     * @param board  the board itself
     * @param size   the width and height of the board
     * @param player the player, 'X' or 'O'
     * @return true if the specified player has won
     */
    private boolean checkWinner(char[][] board, int size, char player) {
        // check each column
        for (int x = 0; x < size; x++) {
            int total = 0;
            for (int y = 0; y < size; y++) {
                if (board[x][y] == player) {
                    total++;
                }
            }
            if (total >= size) {
                return true; // they win
            }
        }

        // check each row
        for (int y = 0; y < size; y++) {
            int total = 0;
            for (int x = 0; x < size; x++) {
                if (board[x][y] == player) {
                    total++;
                }
            }
            if (total >= size) {
                return true; // they win
            }
        }

        // forward diag
        int total = 0;
        for (int x = 0; x < size; x++) {
            for (int y = 0; y < size; y++) {
                if (x == y && board[x][y] == player) {
                    total++;
                }
            }
        }
        if (total >= size) {
            return true; // they win
        }

        // backward diag
        total = 0;
        for (int x = 0; x < size; x++) {
            for (int y = 0; y < size; y++) {
                if (x + y == size - 1 && board[x][y] == player) {
                    total++;
                }
            }
        }
        if (total >= size) {
            return true; // they win
        }

        return false; // nobody won
    }

    /**
     * Disables all the buttons in the grid.
     */
    private void disableButtons() {
        TableLayout T = (TableLayout) findViewById(R.id.tableLayout);
        for (int y = 0; y < T.getChildCount(); y++) {
            if (T.getChildAt(y) instanceof TableRow) {
                TableRow R = (TableRow) T.getChildAt(y);
                for (int x = 0; x < R.getChildCount(); x++) {
                    if (R.getChildAt(x) instanceof Button) {
                        Button B = (Button) R.getChildAt(x);
                        B.setEnabled(false);
                    }
                }
            }
        }
    }

    /**
     * This will add the OnClickListener to each button inside out TableLayout
     */
    private void setupOnClickListeners() {
        TableLayout T = (TableLayout) findViewById(R.id.tableLayout);
        for (int y = 0; y < T.getChildCount(); y++) {
            if (T.getChildAt(y) instanceof TableRow) {
                TableRow R = (TableRow) T.getChildAt(y);
                for (int x = 0; x < R.getChildCount(); x++) {
                    View V = R.getChildAt(x); // In our case this will be each button on the grid
                    V.setOnClickListener(new PlayOnClick(x, y));
                }
            }
        }
    }

    /**
     * Custom OnClickListener for Noughts and Crosses<br />
     * Each Button for Noughts and Crosses has a position we need to take into account
     *
     * @author Lyndon Armitage
     */
    private class PlayOnClick implements View.OnClickListener {

        private int x = 0;
        private int y = 0;

        public PlayOnClick(int x, int y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public void onClick(View view) {
            if (view instanceof Button) {
                Button B = (Button) view;
                board[x][y] = noughtsTurn ? 'O' : 'X';
                B.setText(noughtsTurn ? "O" : "X");
                B.setEnabled(false);
                noughtsTurn = !noughtsTurn;

                // check if anyone has won
                if (checkWin()) {
                    disableButtons();
                }
            }
        }
    }
}

Answer 1

• Use case diagram for the definition of the scope.
• State machine/chart for defining the logic of use
• package diagram for start the planning the placement of classes and sources
• Class diagrams for classes supporting the logic
• Sequence diagrams for algorithms used
• Composite structure diagrams for planning the complex classes.

If some diagram is absolutely obvious, you needn't do it.

But! AFTER the coding you don't need diagrams already, rather good javadocs.

If it is not your code and you want to understand it, diagrams can help. Start from drawing the more simple ones, and continue to these you understand the worst.

For the case when it IS your code and you want to change it, draw diagrams on the conceptions that you want to refactor.

Answer 2

The correct type of UML diagram you need to use depends on the what you need to convey and who your target audience are.

For example: 1) If you need to show the process level activities (at a high level), I would recommend using Activity Diagrams. These are good for communicating with both technical folks as well as analysts and users.

2) If you would like to show the how the flow occurs at the object level, Sequence Diagrams will be more appropriate. The target audience in this case will be developers.

Let us know the intend and we can quickly help you with most relevant answer.