Java SCJP 8

What is the result?

1.      package path.pkg.a

2.      class Animal {

3.          Animal(){

4.             System.out.println(„Hellow Animal“);

5.          }

6.          void makeNoise() { System.out.println( „generice noise“ ); }

7.      }

8.       

9.      package path.pkg.b

10.   class Doc extends Animal {

11.      Doc() {

12.           super();

13.      }

14.      void makeNoise() { System.out.println( “Bark”); }

15.      void playDEad() { Syste.out.println( “roll over”); }

16.   }

17.    

18.   package path.pkg.b

19.   class DocTest {

20.      public static void main(String[] args) {

21.          Doc doc = new Doc();

22.          doc.makeNoise();

23.      }

24.   }

What ist the result?

1.      class Foo {

2.          int x = 3;

3.          float y = 4.4f;

4.          public static void main(String… args) {

5.               for( int z=x; z <++x; z--, y=y+z ) {

6.                     System.out.println(“x is “ + x);

7.                     System.out.println(“y is “ + y);

8.               }

9.               System.out.println(“ENDE”);

10.       }

11.   }

Welche Aussagen sind richtig?

What ist the result?

Given:

3.      class Dog {

4.           public void bark() { System.out.print( “woof “); }

5.      }

6.      class Hound extends Dog {

7.           public void sniff() { System.out.print(“sniff “); }

8.           public void bark() { System.out.print(“howl “); }

9.      }

10.   public void DogShow {

11.        public static void main(String… args) { new DogShow().go(); }

12.        void go() {

13.             new Hound().bark();

14.             ((Dog) new Hound()).bark();

15.             ((Dog) new Hound()).sniff();

16.       }

17.   }

(SCPJ 6, Seite175)

What ist the result?

Given:

class Clidder {

     private final void flipper() { System.out.print(“Clidder ”); }

}

public class Clidlet extends Clidder {

     public final void flipper() { System.out.print(“Clidlet ”); }

     public static void main(String[] args) {

          new Clidlet().flipper();

     }

}

(SCPJ 6, Seite 172)

What is the restul?

Given:

public class Redwood extends Tree {

     public static void main(String[] args) {

          new Redwood().go();

     }

     void go() {

          go2(new Tree(), new Redwood());

          go2( (Redwood) new Tree(), new Redwood());

     }

     void go2(Tree t1, Redwood r1) {

          Redwood r2 = (Redwood) t1;

          Tree t2 = (Tree) r1;

     }

class Tree { }

(SCJP 6, page 176)

What is the restul?

Given:

3.      class Mammal {

4.            String name = “furry “;

5.            String makeNoise() { return “generic noise”; }

6.      }

7.      class Zebra extends Mammal {

8.            String name = “stripes “;

9.            String makeNoise() { return “bray”; }

10.   }

11.   public class ZooKeeper {

12.         public static void main(String[] args) { new ZooKeeper().go(); }

13.         void go() {

14.               Mammal m = new Zebra();

15.               System.out.println( m.name + “ “ + m.makeNoise() );

16.         }

17.   }

(SCJP 6, page 179)

What is the restul?

Given:

3.      class A { }

4.      class B extends A { }

5.      public class ComingThru {

6.           static String s = “-“;

7.           public static void main(String[] args) {

8.                A[] aa = new A[2];

9.                B[] bb = new B[2];

10.             sifter(aa);

11.             sifter(bb);

12.             sifter(7);

13.             System.out.println(s);

14.        }

15.        static void sifter(A[]… a2) { s += “1”; }

16.        static void sifter(B[]… b2) { s += “2”; }

17.        static void sifter(B[] b1) { s += “3”; }

18.        static void sifter(Object o) { s += “4”; }

19.   }

(SCJP 6, page 179)

Stack/Heap: Witch is true?

Assingment: Which result ist correct?

class Bird {
    { System.out.print("b1 "); };
    static { System.out.print("b2 "); };
    public Bird() { System.out.print("b3 "); };
}

class Raptor extends Bird {
    static { System.out.print("r1 "); };
    public Raptor() { System.out.print("r2 "); };
    { System.out.print("r3 "); };
    static { System.out.print("r4 "); };
}

public class Hawk extends Raptor {
    public static void main(String... args){
        System.out.print("pre ");
        new Hawk();
        System.out.print("hawk ");
    }
}

(SCJP 6, page 281)

Which are ture?

Give:

3.   public class Bridge {
4.      public enum Suits{
5.          CLUBS(20), DIAMONDS(20), HEARTS(30), SPADES(30),
6.          NOTRUMP(40) { public int getValue(int bid) {
                        return ((bid-1)*30)+40; } };
7.          Suits(int points) { this.points = points; }
8.          private int points;
9.          public int getValue(int bid) { return points * bid; }
10.    }
11.    public static void main(String[] args){
12.            System.out.println(Suits.NOTRUMP.getValue(3));
13.            System.out.println(Suits.SPADES + " " + Suits.SPADES.points );
14.            System.out.println(Suits.values());
15.        }
16.    }

(SCJP 6, page 281)

When line 16 is reached, how many objects will be eligible for garbage collection?

Given:

3.     public class Beta { }

4.     public class Alpha {

5.          static Beta b1;

6.          Beta b2;

7.     }

8.     public class Tester {

9.          public static void main( String [] args ) {

10.              Beta b1 = new Beta();

11.              Alpha a1 = new Alpha();

12.              a1.b1 = b1;

13.              a1.b2 = b1;

14.              a2.b2 = b2;

15.              a1 = null; a2 = null; b2 = null;    

16.              // do stuff

17.        }

18.    }

(SCJP 6, page 284)

What is the result?

Given:
3.    class Box {
4.        int size;
5.        Box(int s) { size = s; }
6.    }
7.    public class Laser {
8.        public static void main(String[] args) {
9.            Box b1 = new Box(5);
10.           Box[] ba = og(b1, new Box(6) );
11.           ba[0] = b1;
12.           for(Box b : ba) System.out.print( b.size + “ “ );
13.       }
14.   static Box[] go(Box b1, Box b2) {
15.       b1.size. = 4;
16.       Box[] ma = {b2, b1};
17.       return ma;
18.   }

(SCPJ 6, page 285)

Zähle die primitive Datentypen auf?

Welches primitiven Datentypen sind vorzeichenbehaftete Ganzzahl-Datentyp

Wieviel Speicher benötigt der Datentyp in Bit:

• byte

Wieviel Speicher benötigt der Datentyp in Bit:

• short

Wieviel Speicher benötigt der Datentyp in Bit:

• int

Wieviel Speicher benötigt der Datentyp in Bit:

• long

Wieviel Speicher benötigt der Datentyp in Bit:

• float

Wieviel Speicher benötigt der Datentyp in Bit:

• double

Which rules for legal identifiers are valid