Game15, MainActivity.java

package com.example.mygame15board;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    Random rnd = new Random();
    Button[][] btns = new Button[4][4];
    int emptyRow, emptyCol;

    MySoundPool myPool;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                int btnId = getResources().getIdentifier("button" + r + c, "id", this.getPackageName());
                btns[r][c] = findViewById(btnId);
                btns[r][c].setOnClickListener(this);
            }
        }

        putNumbers();
        myPool = new MySoundPool(this);
    }

    public void orderTheBoard(View v) {
        int i = 1;
        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                //btns[r][c].setText((4*r+c) + "");
                btns[r][c].setText(i + "");
                i = (i + 1) % 16;
            }
        }

        btns[emptyRow][emptyCol].setVisibility(View.VISIBLE);

        btns[3][3].setVisibility(View.INVISIBLE);
        emptyRow = 3;
        emptyCol = 3;
    }

    @Override
    public void onClick(View v) {
        int clickedRow = -1, clickedCol = -1;
        // find cliced row and column
        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                if (btns[r][c].getId() == v.getId()) {
                    clickedRow = r;
                    clickedCol = c;
                }
            }
        }

        if (canMove(clickedRow, clickedCol)) {
            myPool.playClickOk();

            // set visibility
            v.setVisibility(View.INVISIBLE);
            btns[emptyRow][emptyCol].setVisibility(View.VISIBLE);

            // switch texts
            btns[emptyRow][emptyCol].setText(((Button) v).getText().toString());
            ((Button) v).setText("0");

            // update emptyRow and emptyCol
            emptyRow = clickedRow;
            emptyCol = clickedCol;

            // check if game is over
            if (gameIsOver()) {
                myPool.playGameOver();
                Toast.makeText(this, "Game is over!", Toast.LENGTH_SHORT).show();
                // finish();
                for (int r = 0; r < 4; r++) {
                    for (int c = 0; c < 4; c++) {
                        //btns[r][c].setEnabled(false);
                        btns[r][c].setOnClickListener(null);
                    }
                }

            }
        } else {
            myPool.playClickError();
        }
    }

    private boolean canMove(int clickedRow, int clickedCol) {
        if (clickedRow == emptyRow && (clickedCol == emptyCol + 1 || clickedCol == emptyCol - 1))
        //if (clickedRow==emptyRow && Math.abs(clickedCol- emptyCol)==1)
        {
            return true;
        }

        if (clickedCol == emptyCol && (clickedRow == emptyRow + 1 || clickedRow == emptyRow - 1)) {
            return true;
        }

        return false;
    }

    private boolean gameIsOver() {
        int i = 1;
        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                int no = Integer.parseInt(btns[r][c].getText().toString());
                if (no == i)
                    i = (i + 1) % 16;
                else
                    return false;
            }
        }
        return true;
    }

    public void putNumbers() {
        int i = 0;
        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                //btns[r][c].setText((4*r+c) + "");
                btns[r][c].setText(i + "");
                i++;
            }
        }

        // switch numbers on buttons 20 up to times
        int switchCount = rnd.nextInt(20);
        for (i = 0; i < switchCount; i++) {
            int n1 = rnd.nextInt(16);
            int n2 = rnd.nextInt(16);

            while (n1 == n2) {
                n2 = rnd.nextInt(16);
            }

            // switch buttons
            Button b1, b2;
            b1 = btns[getRow(n1)][getCol(n1)];
            b2 = btns[getRow(n2)][getCol(n2)];

            String temp = b1.getText().toString();
            b1.setText(b2.getText().toString());
            b2.setText(temp);
        }

        // hide button with zero
        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                if (btns[r][c].getText().toString().equals("0")) {
                    btns[r][c].setVisibility(View.INVISIBLE);
                    emptyRow = r;
                    emptyCol = c;
                }
            }
        }
    }

    private int getRow(int n) {
        return n / 4;
    }

    private int getCol(int n) {
        return n % 4;
    }

    public void restart(View view) {
        btns[emptyRow][emptyCol].setVisibility(View.VISIBLE);
        putNumbers();
        for (int r = 0; r < 4; r++) {
            for (int c = 0; c < 4; c++) {
                btns[r][c].setOnClickListener(this);
            }
        }
    }
}