OCP

Pour quelle classe la méthode main compilerai ?

 

public static void main(String[] args) {
   BigCat cat = new BitCat();
   System.out.println(cat.name);
}

package cat;
public class BigCat {
   public String name = "cat";
}

package cat.species;
public class Lynx extends BigCat {}

package cat;
public class CatAdmirer {}

package mouse;
public class Mouse {}

Pour quelle classe la méthode main compilerai ?

 

public static void main(String[] args) {
   BigCat cat = new BitCat();
   System.out.println(cat.hasFur);
}

package cat;
public class BigCat {
   protected boolean hasFur = true;
}

package cat.species;
public class Lynx extends BigCat {}

package cat;
public class CatAdmirer {}

package mouse;
public class Mouse {}

Pour quelle classe la méthode main compilerai ?

 

public static void main(String[] args) {
   BigCat cat = new BitCat();
   System.out.println(cat.hasPawn);
}

package cat;
public class BigCat {
   boolean hasPawn = true;
}

package cat.species;
public class Lynx extends BigCat {}

package cat;
public class CatAdmirer {}

package mouse;
public class Mouse {}

Pour quelle classe la méthode main compilerai ?

 

public static void main(String[] args) {
   BigCat cat = new BitCat();
   System.out.println(cat.hasPawn);
}

package cat;
public class BigCat {
   private int id;
}

package cat.species;
public class Lynx extends BigCat {}

package cat;
public class CatAdmirer {}

package mouse;
public class Mouse {}

Quel ligne est une redéfinition ?

 

class Bobcat {
   public void findDen() { }
}

class BobcatKitten extends Bobcat {
   public void findDen() { }
   public void findDen(boolean b) { }
   public int findden() throws Exception { return 0; }
}

Quel ligne est une surcharge ?

class Bobcat {
   public void findDen() { }
}

class BobcatKitten extends Bobcat {
   public void findDen() { }
   public void findDen(boolean b) { }
   public int findden() throws Exception { return 0; }
}

Quel(les) ligne(s) ne compile(nt) pas ?

 

class Bobcat {
   public void findDen() { }
}

class BobcatKitten extends Bobcat {
   public void findDen() { }
   public void findDen(boolean b) { }
   public int findden() throws Exception { return 0; }
}

Par quel ligne peut-on remplacer la ligne en pointillé ?

 

abstract class Cat {
   ---------------------
}

class Lion extends Cat {
   void clean() {}
}

Sur quelle(s) ligne(s) peut-on ajouter des mots clés 'final' ?

abstract class Cat {
   String name = "The Cat";
   void clena() {}
}
class Lion extends Cat {
   void clean() {}
}

Sur quelle(s) ligne(s) peut-on ajouter des mots clés 'static' ?

 

abstract class Cat {
   String name = "The Cat";
   void clean() {}
}
class Lion extends Cat {
   void clean() {}
}

Quelle(s) import(s) est (sont) obligatoire pour que le code compile ?

 

class ListHelper {
   public List<String> copyAndSortList(List<String> original) {
      List<String> list = new ArrayList<String>(original);
      sort(list);
      return list;
   }
}

Que va afficher le code suivant ?

 

static class HeavyAnimal {}
static class Hippo extends HeavyAnimal {}
static class Elephant extends HeavyAnimal {}

public static void main(String[] args) {
   HeavyAnimal heavyAnimal = new Hippo();
   Hippo hippo = new Hippo();
   Elephant elephant = new Elephant();
   System.out.println(heavyAnimal instanceof HeavyAnimal);
   System.out.println(heavyAnimal instanceof Hippo);
   System.out.println(heavyAnimal instanceof Elephant);
   System.out.println(hippo instanceof HeavyAnimal);
   System.out.println(hippo instanceof Hippo);
}

Que va afficher le code suivant ?

 

static class HeavyAnimal {}
static class Hippo extends HeavyAnimal {}
static class Elephant extends HeavyAnimal {}

public static void main(String[] args) {
   HeavyAnimal heavyAnimal = new Hippo();
   Hippo hippo = new Hippo();
   Elephant elephant = new Elephant();
   System.out.println(heavyAnimal instanceof Hippo);
   System.out.println(heavyAnimal instanceof Elephant);
   System.out.println(elephant instanceof HeavyAnimal);
   System.out.println(elephant instanceof Hippo);
}

Que va afficher le code suivant ?

 

interface Mother {}
static class HeavyAnimal {}
static class Hippo extends HeavyAnimal {}
static class Elephant extends HeavyAnimal {}

public static void main(String[] args) {
   HeavyAnimal heavyAnimal = new Elephant();
   Hippo hippo = new Hippo();
   Elephant elephant = new Elephant();
   System.out.println(heavyAnimal instanceof Mother);
   System.out.println(heavyAnimal instanceof Elephant);
   System.out.println(elephant instanceof HeavyAnimal);
   System.out.println(elephant instanceof Mother);
}