1
0
mirror of https://gitlab.com/magicalsoup/Highschool.git synced 2025-01-23 16:11:46 -05:00

Add new file

This commit is contained in:
James Su 2019-09-18 16:09:13 +00:00
parent cf47430de5
commit 9c10a3791b

View File

@ -0,0 +1,71 @@
# 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
```java
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
```java
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
```
## Pass-By-Reference