20200414

package com.test;
class A {
    void aMethod() { System.out.println("aMethod"); }
} 
class B extends A {
    void bMethod() { System.out.println("bMethod"); }
}
public class Test1 {
    public static void main(String[] args) {
        B b = new B();
        String className = b.getClass().getSimpleName();
        System.out.println(className);
        if(className.equals("B")) {
            System.out.println("B O.k");
        }
        if(b instanceof B) {
            System.out.println("B O.k2");
        }
        boolean check1 = b instanceof A;
        System.out.println(check1);
        B b1 = null;
        boolean check2 = b1 instanceof A;
        System.out.println(check2);
        
    }
}
///////////////////////////////////////////////////////////
package com.test;
class Animal {
    void breath() {System.out.println("Animal breath");}    
}
class Dog extends Animal {
    void bark() {System.out.println("Bark breath");}
}
public class Test2 {
    public static void main(String[] args) {
        
        Dog d = new Dog();    
        Animal a = new Animal();
        test(d);
        test(a);
    }
    static void test(Animal a) {
        if(a instanceof Dog) {
            System.out.println("Dog");
        }
        else if(a instanceof Animal) {
            System.out.println("Animal");
        }
    }
}
///////////////////////////////////////////////////////////
package com.test;
class MyClass {
    String m;
    void mMethod() {}
}
public class Test3 {
    public static void main(String[] args) {
        int[] arr;
        arr = new int[3];        
        int[] arr2 = new int[3];
        arr2[0] = 1;
        arr2[1] = 2;
        arr2[2] = 3;
        
        for(int inx = 0; inx < arr2.length; inx++) {
            System.out.println(arr2[inx]);
        }
        
        MyClass[] arr3;
        arr3 = new MyClass[3];
        arr3[0] = new MyClass();
        arr3[1] = new MyClass();
        arr3[2]    = new MyClass();
        arr3[0].m = "홍길동";
        System.out.println(arr3[0].m);
    }
}
 
///////////////////////////////////////////////////////////
 
package com.test;
class Box extends Object {
    String name;
    public Box(String name) {
        this.name = name;
    }
    public String toString() {
        return this.name;
    }
}
public class Test4 {
    static void println2(Object o) {
        System.out.println(o.toString());
    }
    public static void main(String[] args) {
        Box[] arrBoxes = new Box[2];
        arrBoxes[0] = new Box("빨간색");
        arrBoxes[1] = new Box("하얀색");
        System.out.println(arrBoxes[0]);
        System.out.println(arrBoxes[1]);
        println2(arrBoxes[0]);
        println2(arrBoxes[1]);
    
        
        
    }
}
///////////////////////////////////////////////////////////
package com.test;
public class Test5 {
    public static void main(String[] args) {
        int[] arr = new int[3];
        arr[0] = 1;
        arr[1] = 2;
        arr[2] = 3;
        for(int inx = 0; inx < arr.length; inx++) {
            System.out.println(arr[inx]);
        }
        for(int a : arr) {
            System.out.println(a);
        }
        String[] strs = {"이순신", "홍길동", "강감찬"};
        for(String nm : strs) {
            System.out.println(nm);
        }
        
 
    }
 
}