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class C {
 
	public static String print(A a) {
		return "A: " + a.toString();
	}
 
	public static String print(B b) {
		return "B: " + b.toString();
	}
 
	public static void swap(A a1, A a2) {
		A c = a2;
		a2 = a1;
		a1 = c;
	}
 
	public static void swap(A[] as, int index1, int index2) {
		A c = as[index2];
		as[index2] = as[index1];
		as[index1] = c;
	}
 
	public static void main(String[] args) {
		A o1 = new A(1);
		B o2 = new B(2);
		A o3 = new B(o1.getA() + o2.getA() + o2.getB());
 
		swap(o1, o2);
		swap(o2, o3);
 
		A[] as = { o1, o2, o3 };
 
		swap(as, 0, 1);
		swap(as, 1, 2);
 
		o1.add(o2);
		o3.add(o2);
		o2.add(o3);
		o3.add();
 
 
		System.out.println(print(o1));
		System.out.println(print(o2));
		System.out.println(print(o3));
 
		A a1 = as[o1.getA() % as.length];
		A a2 = as[o2.getA() % as.length];
		A a3 = as[o3.getA() % as.length];
 
		System.out.println(print(a1) + a1.getA());
		System.out.println(print(a2) + a2.getA());
		System.out.println(print(a3) + a3.getA());
 
	}
}



public class B extends A{
 
	private int b;
 
	public B(int wert) {
		super(wert);
	}
 
	public void add(B b) {
		this.b += b.getA();
	}
 
	public void add() {
		this.b += 2;
	}
 
	public int getB() {
		return this.b;
	}
 
	public String toString() {
		return "B" + this.getB();
	}
}



public class A {
 
	private int a;
 
	public A(int wert) {
		this.a = wert;
	}
 
	public void add(A a) {
		this.a += a.getA();
	}
 
	public void add() {
		this.a += 1;
	}
 
	public int getA() {
		return this.a;
	}
 
	public String toString() {
		return "A" + this.getA();
	}
}

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class C {

public static void main(String[] args) {
A o1 = new A(1); // o1.a=1
B o2 = new B(2); // o1.a=2
A o3 = new B(o1.getA() + o2.getA() + o2.getB()); //o3.a=o1.a+o2.a+o2.b = 1+2+0 = 3

swap(o1, o2); // bewirkt nichts, da in swap() nur referenzen der eigenen variablen ausgetauscht werden
swap(o2, o3);

A[] as = { o1, o2, o3 };

swap(as, 0, 1); // as = {o2,o1,o3}
swap(as, 1, 2); // as = {o2,o3,o1}

o1.add(o2); // o1.a= o1.a+o2.a=1+2=3
o3.add(o2); // o3.a= o3.a+o2.a=3+2=5
o2.add(o3); // o2.a=o2.a+o3.a=2+5=7
o3.add(); // o3.b=o3.b +2 = 2


System.out.println(print(o1)); // "A: A3" (o1.a)
System.out.println(print(o2)); // "B: B0" (o2.b)
System.out.println(print(o3)); // "A: B2" (o3.b)

A a1 = as[o1.getA() % as.length]; // A a1=as[3%3] = o2
A a2 = as[o2.getA() % as.length]; // A a2=as[7%3] = o3
A a3 = as[o3.getA() % as.length]; // A a3=as[5%3] = o1

System.out.println(print(a1) + a1.getA()); // "A: B"+o2.b+o2.a =>"A: B07"
System.out.println(print(a2) + a2.getA()); // "A: B"+o3.b+o3.a =>"A: B25"
System.out.println(print(a3) + a3.getA()); // "A: B"+o1.a+o1.a => "A: A33"

}

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public static void swap(A a1, A a2) {
    A c = a2;
    a2 = a1;
    a1 = c;
    a1.add(a2); //a1 und a2, o ist hier unbekannt.
}