Class definition
Member variables: Variable Type Variable Name
Members method: public void method name () {}
Note: The member variables are defined directly outside of class which method
Create an object with class
- Guide package. The need of the class in what position
import package name . Class name
If the class using the class in the same package which guide the package can not write
- Create , format;
Class Name object name = new class name ();
- When used
Use member variables: the object name . Member variable name
Use member method: object name . Member method name (parameters)
The difference between the member variables and local variables
1. Define the position is not the same
Member variables: External Methods
Local variables: internal Method
2. The scope of the role is not the same
Member variables: the whole class can use
Local variables: only internal methods
3. The default values are not the same
Member variables: with default values
Local variables: no default value, operation is not
By keyword private is not free to change the protected member variables
Note: By using private modified, although this class can be freely used, but beyond this class must getTer / setTer access variables and modify variables method.
Indirect access methods naming format getXxx / setXxx
getXxx : no arguments, return type and the same type of member variable
setXxx : no return value, the same parameter type member variable types
Exception: If the basic types of boolean type, getXxx should be changed isXxx format, setXxx unchanged.
this usage
When the member variables local variables and class methods of the same name, because the principle of proximity, will give priority to use local variables, when the need to access the member variable, you can add one in the front this
Format: . The this member variable
Construction method
Constructor method is designed to create an object, when we use the keyword new time to create the object, in fact, call the constructor.
format:
Public class name (parameter type parameter name) {
The method body
}
note:
- Constructor name and class name must be exactly the same.
- The method of construction does not require a return value
- Also can be overloaded constructor
Standard class and shortcuts
Standard class format:
- All member variables must be private modification.
- Each variable must be a member of a pair of Setter / Getter methods
- Writing a no-argument constructor
- Write a constructor parameter
A key generation Setter / Getter Method:
Lnsert + alt , select Setter and Getter , hold down the shift select all variables point ok
Write a constructor with no arguments:
Lnsert + alt , selection constructor , selection select none
Write a constructor argument:
Lnsert + alt , select the constructor , select all the variables, the ok
Write a standard class
Use a standard class