how does 2d array indexing work code example

Example 1: Index through 2d array

int[][]x;//define
for(int i=0;i<x.length;i++){
  for(int j=0;j<x[i].length;j++){
    //dp something with x[i][j]
  }
}

Example 2: Index through 2d array

int[][]x;//define
for(int []y:x){
  for(int a:y){
    //do something with a
  }
}