Java Arrays

int[] arrayName1; 
  //Declares an array of ints. 
  //note: All elements in an array are the same type
  //  int, String, Object, etc.


int arrayName2[]; 
  //Also declares an array of ints.


int[] arrayName3 = new int[5];  
  //Creates an array of 5 ints, 
  //  initializes all 5 ints to 0.



int[] arrayName4 = {1, 3, 5, 7, 9};  
  //creates an array of 5 ints, values 1,3,5,7,9
  //note: the subscripts of the elements are 0,1,2,3,4
System.out.println("arrayName4[0] = " + arrayName4[0]);          
  //prints arrayName4[0] = 1
System.out.println("arrayName4[4] = " + arrayName4[4]);          
  //prints arrayName4[4] = 9
System.out.println("arrayName4.length = " + arrayName4.length);  
  //prints arrayName4.length = 5

ClassName[] classArrayName1; 
  //Declares an array of ClassName. 


ClassName[] classArrayName2 = new ClassName[5];  
  //Creates an array of 5 ClassName, initializes all 5 to null.

int[] [] matrixName2 = new int[3] [7];                
  //an array of array
int[] [] [] matrixName3 = new int[3] [7] [4];           
  //an array of array of array
int[] [] [] [] matrixName4 = new int[3] [7] [4] [2];  
  //an array of array of array of array

double temp = myArray[i];
myArray[i] = myArray[i+1];
myArray[i+1] = temp;

List list = Arrays.asList(arrayName);
                                
boolean isEqual = Arrays.equals(arrayName, otherArrayName);


Arrays.fill(arrayName, 
            valueToFillWith);


Arrays.fill(arrayName, 
            fromIndex, 
            toIndex, 
            valueToFillWith);


int foundAt = 
  Arrays.binarySearch(arrayName, valueToSearchFor);
  //array must be sorted for this to work


Arrays.sort(Object arrayToSort)
  //All elements in the array must have Comparable interface, 
  //  and they must be comparable to each other.

System.arraycopy(fromArray, 
                 fromOffsetInt, 
                 toArray, 
                 toOffsetInt, 
                 countInt);

Array.get(arrayName, positionInt);


Array.getDouble(arrayName, positionInt);  
//also getBoolean(), getByte(), getChar(), 
//  getFloat(), getInt(), getLong(), getShort()


Array.getLength(arrayName);


Array.set(arrayName, positionInt, value);


Array.setDouble(arrayName, positionInt, doubleToSet);  
//also setBoolean(), setByte(), setChar(), 
//  setFloat(), setInt(), setLong(), setShort()