Tag: java

Questions Related to java

A class cannot be declared:
java

  1. Static

  2. Private

  3. Default

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Correct Option: B

Following code will result in: int a = 3.5;

java

  1. Compilation error

  2. Runtime error

  3. a being 3.5

  4. a being 3.

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Correct Option: A
Explanation:

To solve this question, the user needs to have an understanding of variable types and type casting in programming.

Explanation for each option:

A. Compilation error: This option is correct. In many programming languages, including Java, assigning a floating-point value (such as 3.5) to an integer variable (such as int a) will result in a compilation error. This is because the two types are not compatible, and an explicit type casting is required.

B. Runtime error: This option is incorrect. Runtime errors occur when a program is executed and encounters an error, but in this case, the error would be caught by the compiler during the compilation phase.

C. a being 3.5: This option is incorrect. As mentioned earlier, assigning a floating-point value to an integer variable will result in a compilation error. The value 3.5 cannot be stored in an int variable.

D. a being 3: This option is incorrect. Since the value 3.5 cannot be stored in an int variable, the value of a will not be 3. The code will not compile, so no value will be assigned to a.

Therefore, the correct answer is:

A. Compilation error

Following code will result in: int a1 = 5; double a2 = (float)a1;
java

  1. Compilation error

  2. Runtime error

  3. No errors

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Correct Option: C
Explanation:

To solve this question, the user needs to understand the concept of type casting and data types in programming.

The given code snippet initializes an integer variable a1 with the value 5 and then assigns that value to a double variable a2 after performing a type casting to a float.

Now, let's go through each option and explain why it is right or wrong:

A. Compilation error: This option is incorrect. The code will compile without any errors because type casting from an integer to a float is allowed in most programming languages.

B. Runtime error: This option is incorrect. The code will not result in a runtime error because the type casting from an integer to a float is allowed and will not cause any issues at runtime.

C. No errors: This option is correct. The code will execute without any errors, and the value 5 will be successfully assigned to the a2 variable after the type casting.

Therefore, the correct answer is: C. No errors.

Following code will result in: int a = 9/0;

java

  1. Compilation error: Divisions must be in a try block.

  2. Compilation error: DivideByZeroException

  3. Runtime Exception

  4. No Error: a is NaN

Show answer
Correct Option: C

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) Compilation error: Divisions must be in a try block - This option is incorrect. Divisions do not need to be in a try block. The try-catch block is used to handle exceptions that may occur during the execution of a program, but it is not necessary for all divisions.

Option B) Compilation error: DivideByZeroException - This option is incorrect. The code will compile without any errors.

Option C) Runtime Exception - This option is correct. When dividing an integer by zero, a runtime exception called "ArithmeticException" is thrown. In this case, the code will throw a "ArithmeticException: divide by zero" runtime exception.

Option D) No Error: a is NaN - This option is incorrect. NaN (Not a Number) is a special value in some programming languages that represents an undefined or unrepresentable value. However, in Java, dividing an integer by zero does not result in NaN. It throws an exception instead.

The correct answer is C) Runtime Exception. This option is correct because dividing an integer by zero will result in a runtime exception.

Following code will result in: float a = 9/0;
java

  1. Compilation error: Divisions must be in a try block

  2. Compilation error: DivideByZeroException

  3. Runtime Exception

  4. No Error: a is NaN

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Correct Option: C

A class can be transient
java

  1. True

  2. False

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Correct Option: B

Following code will result in: class A { int b = 1; public static void main(String [] args) { System.out.println("b is " + b); }}

java

  1. Compilation error

  2. Runtime Error

  3. Runtime Exception

  4. Output of b is 1

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Correct Option: A

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) Compilation error - This option is correct. The code will result in a compilation error. The reason is that the variable b is an instance variable of class A, but the main method is a static method. Static methods cannot directly access instance variables. In order to access the instance variable b within the static method main, you would need to create an instance of class A and access the variable through that instance.

Option B) Runtime Error - This option is incorrect. There will not be a runtime error in this code.

Option C) Runtime Exception - This option is incorrect. There will not be a runtime exception in this code.

Option D) Output of b is 1 - This option is incorrect. The code will not compile, so there will be no output.

The correct answer is Option A) Compilation error. This option is correct because the code will result in a compilation error due to the attempt to access the instance variable b within a static method.

Following code will result in: class A { public static void main(String [] args) {B b = new A(); }} class B extends A {}
java

  1. Compile error

  2. Runtime Exception

  3. No error

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Correct Option: A

Following code will result in: class A { public static void main(String [] args) {A a = new B(); }} class B extends A {}
java

  1. Compiler error

  2. Runtime Exception

  3. No errors

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Correct Option: C

Methods that are marked protected can be called in any subclass of that class.
java

  1. True

  2. False

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Correct Option: A