Static 변수 - 기초

Employee.java

public class Employee {

	public static int serialNum = 1000;
	
	private int employeeId;
	private String employeeName;
	private String department;
		
	public int getEmployeeId() {
		return employeeId;
	}
	public void setEmployeeId(int employeeId) {
		this.employeeId = employeeId;
	}
	public String getEmployeeName() {
		return employeeName;
	}
	public void setEmployeeName(String employeeName) {
		this.employeeName = employeeName;
	}
	public String getDepartment() {
		return department;
	}
	public void setDepartment(String department) {
		this.department = department;
	}
	
}

EmployeeTest.java

public class EmployeeTest {

	public static void main(String[] args) {
		Employee employeeLee = new Employee();
		employeeLee.setEmployeeName("이순신");
		System.out.println(employeeLee.serialNum);
		
		Employee employeeKim = new Employee();
		employeeKim.setEmployeeName("김유신");
		employeeKim.serialNum++;
		
		System.out.println(employeeLee.serialNum);
		System.out.println(employeeKim.serialNum);
		
	}
}

 

 

Employee.java 생성자 구현

...

	public Employee()
	{
		serialNum++;
		employeeId = serialNum;
	}

...	

EmployeeTest.java

public class EmployeeTest {

	public static void main(String[] args) {
		Employee employeeLee = new Employee();
		employeeLee.setEmployeeName("이순신");
				
		Employee employeeKim = new Employee();
		employeeKim.setEmployeeName("김유신");
				
		System.out.println(employeeLee.getEmployeeName() + "," + employeeLee.getEmployeeId());
		System.out.println(employeeKim.getEmployeeName() + "," + employeeKim.getEmployeeId());
	}
}

 

 

 

Employee.java

private static int serialNum = 1000;

 ...
public static int getSerialNum() {
	return serialNum;
}

public static void setSerialNum(int serialNum) {
	Employee.serialNum = serialNum;
}

 

Employee.java

public static void setSerialNum(int serialNum) {
		int i = 0;
		
		employeeName = "Lee";  //오류발생
		Employee.serialNum = serialNum;
	}

EmployeeTest2.java

public class EmployeeTest2 {

	public static void main(String[] args) {

		System.out.println(Employee.getSerialNum());
		Employee.setSerialNum(1003);
		System.out.println(Employee.getSerialNum());
	}
}