A sentimental robot

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 import java.util.Scanner; public class Day10_03 { public static void main(String[] args) { Cl[] cl; int n1; int n2; System.out.println("=== Score Management ==="); Scanner sc = new Scanner(System.in); System.out.println("몇 반을 입력할까요? : "); n1 = sc.nextInt(); cl = new Cl[n1]; for (int i = 0; i

package Network; import java.util.*; import java.io.*; import java.net.*; public class Multi { HashMap client; Multi() { client = new HashMap(); Collections.synchronizedMap(client); // wrapping for concurrent access to the map } public static void main(String[] args) { new Multi().start(); } // main public void start() { ServerSocket serverSocket = null; Socket socket = null; try { serverSocket ..

package Network; import java.io.*; import java.net.*; import java.util.Scanner; class Sender extends Thread { Socket socket; DataOutputStream out; String identifier; Sender(Socket socket, String id) { this.socket = socket; identifier = "[" + id + ":" + socket.getPort() + "] says:"; try { out = new DataOutputStream(socket.getOutputStream()); } catch (IOException e) { e.printStackTrace(); } } publ..

NullPointerException 참조 변수가 null값을 가지고 있을 때, 객체의 필드나 메소드를 사용하려고 할 때 발생 int [] arr = null; int arr[0] = 10; // NullPointerException 있지도 않은 객체에 필드를 저장하려함 String str = null; System.out.println("총 문자의 수 :" + str.length()); // NullPointerException 있지도 않은 객체의 메소드 사용하려함

package Pack01; import javafx.scene.control.Button; import javafx.scene.control.TextArea; import javafx.scene.control.TextField; import javafx.application.Application; import javafx.application.Platform; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.scene.Scene; import javafx.scene.layout.VBox; import javafx.stage.Stage; public class Hello extends Application {..

package Pack01; import javafx.scene.control.Button; import javafx.scene.control.TextArea; import javafx.scene.control.TextField; import javafx.application.Application; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.scene.Scene; import javafx.scene.layout.VBox; import javafx.stage.Stage; public class Hello extends Application { @Override public void start(Stage a..

import javafx.application.Application; import javafx.stage.Stage; public class Hello extends Application { @Override public void init() throws Exception { System.out.println("initiate"); } @Override public void start(Stage arg0) throws Exception { System.out.println(2); arg0.show(); System.out.println(3); } @Override public void stop() throws Exception { System.out.println("stop"); } public stat..

class A { } public class Day3 { public static void main(String[] args) { A a = new A(); System.out.println(a); // a의 16진수 주소값 System.out.println(a.hashCode()); // 10진수 주소값 int n1 = 1234; System.out.println(Integer.toBinaryString(n1)); // 10진수를 2진수로 int n2 = 0x1234; System.out.println(Integer.toBinaryString(n2)); // 16진수를 2진수로 } } public class Day3 { static void func01(int n) { String s1 = Intege..