Conway's Game of Life Java Implementation

Question

Keep state the same if it doesn't fall in the following conditions:

1. Change to 2 if there are exactly 2 ones in the neighbors
2. Change to 3 if there are more than 2 ones in the neighbors

It is also wrapping around so neighbors can be cyclic.

I wrote a basic structure and modularized it to individual functions. I wish to understand better coding techniques and how I can improve.

package code.Misc;
public class changeStateGame {
public static void main(String args[]){
 int current[][] = {
 {0,0,0,0,0,0,0},
 {0,0,0,0,1,0,0},
 {0,0,0,1,1,0,0},
 {0,0,1,1,0,0,0},
 {0,0,0,0,0,0,0}
 };
 int aux [][] = new int [current.length][current[0].length];
 for(int i=0;i<current.length;i++){
 for(int j=0;j<current[0].length;j++){
 aux[i][j]=0;
 }
 }
 System.out.println("Current State");
 printStateGame(current);
 System.out.println("Changed State");
 printStateGame(changeState(current,aux,0,aux[0].length));
}
public static void printStateGame(int a[][]){
 for(int i=0;i<a.length;i++){
 for(int j=0;j<a[0].length;j++){
 System.out.print(a[i][j]+" ");
 }
 System.out.println();
 }
}
public static int [][] changeState(int c[][],int a[][], int row, int col){
 for(int i=0;i<a.length;i++){
 for(int j=0;j<a[0].length;j++){
 a[i][j]=checkNeighbors(c,i,j);
 }
 }
 return a;
}
public static int checkNeighbors(int a[][],int row,int col){
 int neighborCount = 0;
 for(int i=row-1;i<row+1;i++){
 for(int j=col-1;j<col+1;j++){
 if (i < 0)
 i = a.length - 1;
 if (j < 0)
 j = a[0].length - 1;
 if (i == a.length)
 i = 0;
 if (j == a[0].length)
 j = 0;
 if(i==row){
 if(j==col){
 continue;
 }
 }
 if(j==col){
 if(i==row){
 continue;
 }
 }
 neighborCount += checkElement(a[i][j]);
 }
 }
 return modifyElement(a[row][col],neighborCount);
}
public static int checkElement(int a){
 if(a==1)
 return 1;
 else
 return 0;
}
public static int modifyElement(int a, int count){
 if(count<2){
 return a;
 }
 else if (count == 2){
 return 2;
 }
 else {
 return 3;
 }
}
}

• Vogel612: Welcome to Code Review! Please do not update the code in your question to incorporate feedback from answers, doing so goes against the Question + Answer style of Code Review. This is not a forum where you should keep the most updated version in your question. Please see [what you may and may not do after receiving answers](meta.codereview.stackexchange.com/a/1765" data-ss1465891299="1).

Answer 1

Bug 1

Your neighbor counting loops are only iterating twice instead of three times, so you aren't counting neighbors to the right or below.

Bug 2

If you were to correct Bug 1, your program would infinite loop in checkNeighbors because you modify your loop variables inside the loop when they wrap around. So for example, if col is the rightmost column, you will set j to 0 inside the loop which will cause the j loop to never terminate.

Bug 3

You sometimes set your array elements to 2 or 3. But in Life, each array element should be 0 or 1 only. Your modifyElement function is incorrect.

Dead code

These two blocks of code are identical, so the second is useless:

 if(i==row){
 if(j==col){
 continue;
 }
 }
 if(j==col){
 if(i==row){
 continue;
 }
 }

Unused arguments

The changeState function has two unused arguments: row and col.

• bobbel: For your last point, unused arguments, is there a possibility to tell the compiler to warn about unused method parameters? I'm working with eclipse, so if you can't tell your compiler directly, is there a good plugin for this?