How do you declare an array variable?

datatype [] arrayName;

(double [] myList)

datatype [] arrayName = new datatype [arraySize]

((( e.g., double [] myList = new double [10] )))

        double[] myList = {1.9, 2.9, 3.4, 3.5};

equivalent to:

       double[] myList = new double[4];

       myList[0] = 1.9;

       myList[1] = 2.9;

       myList[2] = 3.4;

       myList[3] = 3.5; 

splitting it:

double [] myList;

myList = {1.9, 2.9, 3.4, 3.5 } 

How do you copy an array? 

How would you do it using a loop?

int [] sourceArray = { 2, 3, 1, 5, 10 }

int [] targetArray = new int [sourceArray.length];

When copying an array, use the assignment statement: (=)

list2 = list1;

Pass By Value

What's the difference between passing a primative variable type and a reference variable type (i.e., an array variable)

- When passing a primative type to a method (double, char, int, boolean), the variable's value is passed, and any changes to the value within the method do not change the value of the argument outside of the method.

- When passing a reference type to a method (array, interface, class), the variable's value is passed--which is a reference point to the argument outside of the method. As a result, any changes made to the array via the parameter array variables passed inside of the method do affect the argument array outside of the method.

dataType [] [] refVar;

((( e.g., double [] [] myList; )))

dataType [] [] refVar = new dataType [10] [10]

((( double [] [] myList = new double [10] [10] ))) 

double [] [] myList = {

                                 {1, 2, 3}, 

                                 {4, 5, 6},

                                 {7, 8, 9},

                                 {10, 11, 12},

                               };

public static int userHand (int num1, int num2)

       ^        ^        ^             ^          ^

       |         |          |              |

    modifier   return value type    method name         parameter list - formal parameters

Formal Parameters = variables defined in the method header.

(((( int num1, int num2 ))))

Actual parameter = (argument) the value passed to the method parameters when a method is invoked.

((((( max (x, y); ))))

A void method returns no value.

public static void printStars (int n) 

{

   for (int i = 0; i < n; i++)

   system.out.print("*");

}

//no return statement needed, or, "return: ___"

What is wrong with this non-void method example?

public static int sign (int n)

{ 

   if (n > 0)

      system.out.println(n);

   else

      return 0;

}

A return statement is required for a nonvoid method.

To fix this problem, add a return in the "if" branch, or, after the "if-else" statement entirely

When an actual parameter is passed to a method, its value is copied into the formal paramater.

In other words, the actual parameter(argument) is a copy of the formal parameter (parameters)

EXAMPLE:

[image]

The part of the program where the variable can be seen/referenced.

Example:

[image]

The scope of a local variable starts from its declaration and continues to the end of the block that contains the variable. 

defining two or more methods, within the same class, that share the same name, as long as their parameter declarations are different. When this is the case, the methods are said to be overloaded, and the process is referred to as method overloading

Example:

public static double piggyButt (double first, double second);

public static double piggyButt (double third, double fourth);

What's the difference between these operators:

-   /

-  %

The division operator (/) divides a type and returns a floating point type (float or double), or integral type.

(e.g.,   10 / 4   has a value of 2 )

The modulus operator (%) returns the remainder of an integer type

(e.g.,   11 % 4   has a value of 3 )