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❓ equals مقابل == مع السلاسل
equals vs == with Strings

String s1 = new String("java");
String s2 = new String("java");
System.out.println(s1.equals(s2) + "," + (s1 == s2));

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❓ equals مقابل == مع السلاسل equals vs == with StringsString s1 = new String("java"); String s2 = new String("java"); System.out.println(s1.equals(s2) + "," + (s1 == s2));

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Anonymous Quiz

54 voters413 views07:39

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❓ أي عبارة صحيحة عن String و StringBuilder؟
Which is true about String vs StringBuilder?

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❓ أي عبارة صحيحة عن String و StringBuilder؟ Which is true about String vs StringBuilder?

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Anonymous Quiz

64%

String is immutable; StringBuilder is mutable

36 voters382 views07:39

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❓ ماذا يطبع جمع عناصر ArrayList؟
What does this ArrayList code print?

import java.util.*;
List<Integer> xs = new ArrayList<>();
xs.add(1);
xs.add(2);
System.out.println(xs.get(0) + xs.get(1));

338 views07:39

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❓ ماذا يطبع جمع عناصر ArrayList؟ What does this ArrayList code print?import java.util.*; List<Integer> xs = new ArrayList<>(); xs.add(1); xs.add(2); System.out.println(xs.get(0) + xs.get(1));

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Anonymous Quiz

43%

27%

30%

IndexOutOfBoundsException

37 voters388 views07:39

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❓ الوراثة مع مُنشئ أب مُعَلَّم
Inheritance with parameterized base constructor

class Base { Base(int x) {} }
class Child extends Base { }

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❓ الوراثة مع مُنشئ أب مُعَلَّم Inheritance with parameterized base constructorclass Base { Base(int x) {} } class Child extends Base { }

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Anonymous Quiz

24%

Compiles successfully

52%

Does not compile: Child must call super(int)

24%

Does not compile: Base needs a no-arg constructor

25 voters364 views07:39

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❓ الفرق بين abstract و interface
Abstract class vs interface

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❓ الفرق بين abstract و interface Abstract class vs interface

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Anonymous Quiz

52%

A class can extend one abstract class and implement multiple interfaces

36%

A class can extend multiple abstract classes

12%

Interfaces cannot have default methods

25 voters362 views07:39

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❓ مستوى الوصول عند إعادة التعريف
Access level when overriding

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❓ مستوى الوصول عند إعادة التعريف Access level when overriding

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Anonymous Quiz

25%

A subclass may widen access (e.g., protected -> public)

50%

A subclass may narrow access (e.g., public -> protected)

25%

Access level must always be identical and cannot widen

24 voters352 views07:39

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❓ التعامل مع الاستثناءات في finally
Try-catch-finally order

try {
  int x = 1 / 0;
  System.out.print("A");
} catch (ArithmeticException e) {
  System.out.print("B");
} finally {
  System.out.print("C");
}

❤1

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❓ التعامل مع الاستثناءات في finally Try-catch-finally ordertry { int x = 1 / 0; System.out.print("A"); } catch (ArithmeticException e) { System.out.print("B"); } finally { System.out.print("C"); }

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Anonymous Quiz

33 voters337 views07:39

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❓ الاستثناءات المُتَحَقَّقة (Checked)
Checked exceptions handling

void read() throws java.io.IOException {}
void m(){ read(); }

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❓ الاستثناءات المُتَحَقَّقة (Checked) Checked exceptions handlingvoid read() throws java.io.IOException {} void m(){ read(); }

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Anonymous Quiz

21%

Compiles: unchecked exceptions only

71%

Does not compile: must handle or declare the checked exception

Runtime error only

24 voters317 views07:39

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❓ تفضيل التحويلات في Overload
Overload preference (widening vs boxing vs varargs)

static void m(long x){ System.out.print("long"); }
static void m(Integer x){ System.out.print("Integer"); }
static void m(int... x){ System.out.print("varargs"); }

m(5);

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❓ تفضيل التحويلات في Overload Overload preference (widening vs boxing vs varargs)static void m(long x){ System.out.print("long"); } static void m(Integer x){ System.out.print("Integer"); } static void m(int... x){ System.out.print("varargs"); } m(5);

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Anonymous Quiz

27 voters321 views07:39

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❓ ترتيب التهيئة: static ثم instance ثم constructor
Initialization order

class X {
  static { System.out.print("S"); }
  { System.out.print("I"); }
  X(){ System.out.print("C"); }
}
new X();

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❓ ترتيب التهيئة: static ثم instance ثم constructor Initialization orderclass X { static { System.out.print("S"); } { System.out.print("I"); } X(){ System.out.print("C"); } } new X();

Choose your answer:

Anonymous Quiz

❤1

31 voters305 views07:39

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❓ إخفاء الحقول (Field Hiding)
Field hiding resolution

class A { int v = 1; }
class B extends A { int v = 2; }
B b = new B();
System.out.println(((A)b).v);

275 views07:39

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