1. Employee 상속

class Employee {
	protected String name;
	protected int age;
	protected String address;
	protected String department;
	protected int salary;
	
	public Employee() {}
	
	public Employee(String mName, int mAge, String mAddress, String mDepartment) {
		name = mName;
		age = mAge;
		address = mAddress;
		department = mDepartment;
	}
	
	public void printInfo() {
		System.out.println("이름 : " + name);
		System.out.println("나이 : " + age);
		System.out.println("주소 : " + address);
		System.out.println("부서 : " + department);
	}
}

class Regular extends Employee {
	public Regular(String mName, int mAge, String mAddress, String mDepartment) {
		super(mName, mAge, mAddress, mDepartment);
	}
	
	public void setSalary(int mSalary) {
		salary = mSalary;
	}
	
	@Override
	public void printInfo() {
		super.printInfo();
		System.out.println("정규직");
		System.out.println("월급 : " + salary);
	}
}

class Temporary extends Employee {
	int workHours;
	int perSalary = 10000;
	
	public Temporary(String mName, int mAge, String mAddress, String mDepartment) {
		super(mName, mAge, mAddress, mDepartment);
	}
	
	public void setWorkHours(int mWorkHours) {
		workHours = mWorkHours;
		salary = workHours * perSalary;
	}
	
	@Override
	public void printInfo() {
		super.printInfo();
		System.out.println("비정규직");
		System.out.println("일한 시간 : " + workHours);
		System.out.println("급여 : " + salary);
	}
}

public class EmployeeTest {

	public static void main(String[] args) {
		Regular r = new Regular("이순신", 35, "서울", "인사부");
		Temporary t = new Temporary("장보고", 25, "인천", "경리부");
		
		r.setSalary(5000000);
		r.printInfo();
		
		t.setWorkHours(120);
		t.printInfo();
	}
}

🟢 super(), super.printInfo()가 이 코드의 포인트!

2. 버블정렬 구현

public class bubbleSort {

	public static int[] bubuleSort(int n, int[] arr) {
		int tmp;
		for(int i = 1; i < n; i++) {
			for(int j = 0; j < (n-i); j++) {
				if(arr[j] > arr[j+1]) {
					tmp = arr[j+1];
					arr[j+1] = arr[j];
					arr[j] = tmp;
				}
			}
		}
		return arr;
	}
	
	public static void main(String[] args) {
		int[] arr = {7,4,5,1,3};
		
		arr = bubuleSort(5, arr);
		
		for(int i = 0; i < 5; i++) {
			System.out.println(arr[i]);
		}
	}
}

🟢 파이썬과는 다르게 tmp변수를 만들어 교체해야 함
🟢 이중 for문에서 n을 1부터 시작한 것과 j < (n-i) 가 포인트 (이해하면 쉬움)

3. getArea() 오버라이딩

class Shape{
	protected int width;
	protected int height;
	
	public Shape(int width, int height) {
		this.width = width; 
		this.height = height;
	}
	
	public double getArea() {
		return (double)width * height;
	}
}

class Rectangle extends Shape {
	
	public Rectangle(int width, int height) {
		super(width, height);
	}
	
	@Override
	public double getArea() {
		return (double)width * height;
	}
}

class Triangle extends Shape {
	
	public Triangle(int width, int height) {
		super(width, height);
	}
	
	@Override
	public double getArea() {
		return width * height / 2.0;
	}
}

public class java_13_p5 {

	public static void main(String[] args) {
		Shape[] shape = {new Triangle(10,10),new Rectangle(10,10)};

        double sumArea = 0;

        for (Shape s : shape) {
            sumArea += s.getArea();
        }

        System.out.println(sumArea);

	}
}

🟢 Rectangle과 Triangle에서 getArea()를 오버라이딩