Learn full JAVA Course from this JAVA Cheatsheet

Single Dimensional or 1-D array is a type of linear array in which elements are stored in a continuous row.

// Initializing
type[] varName= new type[size];

// Declaring
type[] varName= new type[]{values1, value2,...};

Creating an array with random values.

double[] arr = new double[n];
for (int i=0; i<n; i++)
{a[i]= Math.random();}

Searching the max value in the array.

double max = 0;
for(int i=0; i<arr.length(); i++)
 { if(a[i]> max) max = a[i]; }

Reversing an array.

for(int i=0; i<(arr.length())/2; i++)
 { double temp = a[i];
   a[i]= a[n-1-i]; 
   a[n-1-i] = temp;
  }

Two Dimensional or 2-D array is an array of an array where elements are stored in rows and columns.

// Initializing
datatype[][] varName  =  new dataType[row][col];

// Declaring
datatype[][] varName  =  {{value1, value2....},{value1, value2....}..};

Transposing a matrix.

for(i = 0; i < row; i++)
{ for(j = 0; j < column; j++)
  { System.out.print(array[i][j]+" "); }
  System.out.println(" ");
}

Multiplying two matrices.

for (i = 0; i < row1; i++)
{ for (j = 0; j < col2; j++)
  { for (k = 0; k < row2; k++)
    { sum = sum + first[i][k]*second[k][j]; } 
   multiply[i][j]= sum;
   sum = 0;
  }
}