final

4.
class Human{
    private int Hp;
    Human(int Hp){
        this.Hp=Hp;
    }
    public int getHp(){
        return Hp;
    }
    public void setHp(int Hp){
        this.Hp=Hp;
    }
}
class mate extends Human{
    private int mana;
    mate(int Hp,int mana){
       super(Hp);
       this.mana=mana;
   }
    public void setmana(int mana){
        this.mana=mana;
    }
    public int getmana(){
        return mana;
    }
}
class str extends Human{
    private int Def;
    str(int Hp,int Def){
       super(Hp);
       this.Def=Def;
   }
    public void setDef(int Def){
        this.Def=Def;
    }
    public int getDef(){
        return Def;
    }
}
class sup extends Human{
    private int a;
    sup(int Hp,int a){
       super(Hp);
       this.a=a;
   }
    public void seta(int a){
        this.a=a;
    }
    public int geta(){
        return a;
    }
}
public class finals {
    public static void main(String[] args) {
        Human a = new mate(20,2);
        Human b = new str(20,5);
        Human c = new sup(10,10);
    }
}
--------------------------------------------------------------------------------------------------------
5.
public class fors {
public static void num(int i){
    if(i>=0){
        num(i-1);
        if(i%2==0)
            System.out.println("เลขคู่ = "+i);
    }
}
    public static void main(String[] args) {
        num(10000);
    }
}

----------------------------------------------------------------------------------------------------------

6.
public class fors {
public static void num(int i){
    if(i>=0){
        num(i-1);
        if(i%2!=0)
            System.out.println("เลขคี่ = "+i);
    }
}
    public static void main(String[] args) {
        num(10000);
    }
}
------------------------------------------------------------------------------------------------------------
รวมเรื่อยๆ 

public class fors {
public static int num(int i){
    if(i>=0)return i+num(i-1);
    else return 0;
}
    public static void main(String[] args) {
        System.out.println(num(20));
    }
}
---------------------------------------------------------------------------------------------------------------
n!

public class fors {
public static int num(int i){
    if(i>0){
        return i*num(i-1);
    }
    else{
        return 1;
    }
}
    public static void main(String[] args) {
        System.out.println(num(3));
    }
}
-------------------------------------------------------------------------------------------------------------
pow i^2

public class fors {
    public static void loop(int loop){
        for (int i = loop; i>0; i--) {
            for (int j = 0; j< Math.pow(2,loop-i); j++) {
                System.out.print(i);
            }
            System.out.println("");
        }
    }
    public static void main(String[] args) {
       loop(4);
    }
}