2.2 KiB
Methods
What are methods
A java method can be interpreted as a subprogram. It is a collection of statements taht are grouped togehter to perform an operation
Built- in vs User-defined Methods
Built-in: BUild-i nmethods arep art of hte complier package such as system.out.println
Function (return) - Type: it calcualtes and return a value
public static int claculate(int number){procedure-type: executes some commands
Function (return)- type: pubic static return type method name (parameter 1)
procedure-type method: public static void method-name (paramenter 1)
How to create a method
In general, method declarations has 5 basic components (figure 2.): - Modifier: defines access type of the method i.e. from were it can be accessed in your application (For example: public) - The return type: the data type of the value returned by the method or void if it does not return a value (procedure and function type) - Method name: a specific names that identifies the method that can be used to invoke it later - Parameter list: Comma separated list of the input parameter are defined preceded with their data type, within the enclosed parentheses, If there are no parameters, you must use empty parenteses()
Method declaration
- Method body: It is enclosed between braces. the code that you need to be execute to perfrom your intended operations
public int max(int x, int y) {How to call a method (method invocation
To invoke a method you need the method name with the parameter list defined between parentheses
Exammple: Method Name (paramter list)
Must have () parentheses when calling a method, even with no passing parameters
Pass-By-Value
What happens: When a method is called ,a copy of the value of each argument is passed to the method
In the second method: This copy can be changed inside the method, however such a change has no effect on the actual argumnet
int num=10;
double decimal = 5.2;
NumberManeuvers(num decimal);
System.out.println("num = " + num + "and decimal = " + decimal);
public static void numberManeuvers(int i, double j) {
if(i == 10) {
j = 6.2;
i = 12;
}
}
// output = num = 10 and decimal = 5.2