public class Ex18 { public static void main(String[] args){ Vehicle v1 = new Vehicle(); Vehicle v2 = new Vehicle("blue"); System.out.printf("v1: %s %s %d\n", v1.color, v1.gearType, v1.door); System.out.printf("v2: %s %s %d",v2.color, v2.gearType, v2.door); } } class Vehicle{ String color; String gearType; int door; //this

public class Ex17 { public static void main(String[] args){ Car c1 = new Car(); c1.color = "White"; c1.gearType = "Auto"; c1.door = 4; Car c2 = new Car("Black", "Auto", 2); System.out.printf("c1: %s %s %d\n",c1.color, c1.gearType, c1.door); System.out.printf("c2: %s %s %d",c2.color, c2.gearType, c2.door); } } class Car{ String color; String gearType; int door; Car(){} Car(String c, String g, int..

public class Ex16 { Data1 d1 = new Data1(); Data2 d2 = new Data2(); Data2 d3 = new Data2(3); } class Data1{ int value; } class Data2{ int value; Data2(){ value = 100; } Data2(int x){ value = x; } }

public class Ex15 { public static void main(String[] args){ Machine machine = new Machine(); System.out.printf("add(int a, int b): %d\n", machine.add(3,3)); System.out.printf("add(int a, long b): %d\n", machine.add(3,3L)); System.out.printf("add(long a, int b): %d\n", machine.add(3L,3)); } } class Machine{ // 하나의 메서드값에 여러 값의 파라미터 int add(int a, int b){ return a+b; } long add(int a, long b){ retu..

public class Ex14 { int iv = 10; // iv(instance variable) static int cv = 20; //cv(class variable) int iv2 = cv; //static int cv2 = iv; //(X) static int cv2 = new Ex14().iv; //(O) static void sm1(){ // sm(static method) System.out.println(cv); //System.out.println(iv);//(X) System.out.println(new Ex14().iv);//(O) } void im1(){ //im(instance method) System.out.println(cv); System.out.println(iv);..

public class Ex13 { public static void main(String[] args){ // 클래스메서드=스태틱 메서드(객체 생성없이 사용할 수 있는 메서드) System.out.println(Calculator.add(300,200)); System.out.println(Calculator.subtract(300,200)); System.out.println(Calculator.multiple(300,200)); System.out.println(Calculator.divide(300,200)); Calculator caculator = new Calculator(); caculator.a = 300; caculator.b = 200; System.out.println(caculat..

public class Ex10 { public static void main(String[] args){ Data d = new Data(); d.x =10; System.out.println("main():x = "+d.x); Ex10 e = new Ex10(); e.change(d); System.out.println("main():x = "+d.x); } void change(Data d){ d.x = 1000; System.out.println("change():x= "+d.x); } } //Data class in Ex09

public class Ex09 { public static void main(String[] args){ Data d = new Data(); d.x = 10; System.out.println("main():x="+d.x); Ex09 e = new Ex09(); e.change(d.x); System.out.println("main():x=" +d.x); } void change(int x){ x = 1000; System.out.println("challenge():x="+x); } } class Data{ int x; }

public class Ex07 { // 메서드에서 다른 메서드를 호출할 때. public static void main(String[] args){ MethodTest m = new MethodTest(); m.first(); } } class MethodTest{ void first(){ System.out.println("first."); second(); } void second(){ System.out.println("second."); third(); } void third(){ System.out.println("third."); } }

public class Ex05 { // 계산기. public static void main(String[] args){ Calc calc = new Calc(); long result1 = calc.add(5L,3L); long result2 = calc.substract(5L,3L); long result3 = calc.divide(5L,3L); double result4 = calc.multiple(5L, 3L); System.out.printf("%d %d %d %f",result1, result2, result3, result4); } } class Calc{ long add(long a, long b){ long result = a+b; return result; } long substract..

public class Ex04 { public static void main(String[] args){ System.out.println("Card.width: " + Card.width); System.out.println("Card.height: " + Card.height); Card c1 = new Card(); c1.kind = "Heart"; c1.number = 7; Card c2 = new Card(); c2.kind = "Spade"; c2.number = 4; System.out.printf("%s, %d, %d, %d\n", c1.kind, c1.number, c1.width, c1.height); System.out.printf("%s, %d, %d, %d\n", c2.kind,..

public class Ex03 { public static void main(String[] args){ Tv t1 = new Tv(); Tv t2 = new Tv(); System.out.println("t1.channel: "+ t1.channel); System.out.println("t2.channel: "+ t2.channel); t2 = t1; t1.channel = 7; System.out.println("t1.channel: "+ t1.channel); System.out.println("t2.channel: "+ t2.channel); } }