h-elena

package exam;

import java.io.IOException;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/LifeCycleServlet")

public class LifeCycleServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

    public LifeCycleServlet() {

        System.out.println("생성!");

    }

public void init(ServletConfig config) throws ServletException {

System.out.println("init 호출!");

}

public void destroy() {

System.out.println("destroy 호출!");

}

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

System.out.println("service 호출!");

}

}

package exam;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * Servlet implementation class TenServlet

 */

@WebServlet("/Ten")

public class TenServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

    /**

     * @see HttpServlet#HttpServlet()

     */

    public TenServlet() {

        super();

        // TODO Auto-generated constructor stub

    }

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

response.setContentType("text/html; charset=utf-8");

PrintWriter out = response.getWriter();

out.print("<h1> 1-10까지 출력 ! <h1>");

for(int i=1; i<=10; i++){

out.print(i + "<br>"); 

}

out.close();

}

}

public interface Predator {

       public String getFood(); //인터페이스의 메소드는 메소드의 이름과 입출력에 대한 정의만 있고 그 내용은 없다.

}

public class Animal {

       String name;

       public void setName(String name) {

             this.name = name;

       }

}

public class Tiger extends Animal implements Predator {

       public String getFood() {

             return "apple";

       }

}

public class Tiger extends Animal implements Predator {

       public String getFood() {

             return "apple";

       }

}

public class ZooKeeper {

    public void feed(Predator predator) {

        System.out.println("feed " + predator.getFood());

    }

    public static void main(String[] args) {

        ZooKeeper zooKeeper = new ZooKeeper();

        Tiger tiger = new Tiger();

        Lion lion = new Lion();

        zooKeeper.feed(tiger);

        zooKeeper.feed(lion);

    }

}

콘솔 출력내용

feed apple

feed banana

메소드 구조

public 리턴자료형 메소드명(입력자료형1 입력변수1, 입력자료형2 입력변수2, ...){

...

return 리턴값;

}

*리턴자료형이 void면 리턴값 없음

*리턴자료형 public, private, void, static 등

*입력자료형1 입력변수1, 입력자료형2 입력변수2 의 (예시) String name, int a

입력 O 출력 O

public int sum(int a, int b){

     return a+b;

}

public static void main(String[] args) {

     Test myTest = new Test();

     int c = myTest.sum(10, 20);

     System.out.print(c);

}

리턴값받을변수 = 객체.메소드명(입력인수1, 입력인수2, ...)

리턴값이 int로 되어있으므로 c의 자료형은 반드시 int로 해야한다. 

입력 X 출력 O

public class Test {

       public String say() {

             return "Hi";

       }

       public static void main(String[] args) {

             Test myTest = new Test();

             String a = myTest.say();

             System.out.print(a);

       }

}

리턴값받을변수 = 객체.메소드명()

입력 O 출력 X

public class Test {

       public void sum(int a, int b) {

             System.out.println(a+"과 "+b+"의 합은"+(a+b)+"입니다"); //리턴값 아님

       }

       public static void main(String[] args) {

             Test myTest = new Test();

             myTest.sum(3, 4);

       }

}

객체.메소드명(입력인수1, 입력인수2, ...)

리턴값은 return으로만 돌려줘야 함.

입력 X 출력 X

public class Test {

       public void say() {

             System.out.println("Hi");

       }

       public static void main(String[] args) {

             Test myTest = new Test();

             myTest.say();

       }

}

객체.메소드명()