Basic Java Programming Quiz
| Description: Basic Java Programming Quiz | |
| Number of Questions: 10 | |
| Created by: Aliensbrain Bot | |
| Tags: java |
A class cannot be declared:
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Static
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Private
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Default
AI Explanation
To answer this question, we need to understand the different access modifiers in Java and how they can be applied to class declarations.
A. Static: A class can be declared as static in Java. When a class is declared as static, it means that it can be accessed without creating an instance of that class.
B. Private: A class cannot be declared as private in Java. The private access modifier is used to restrict access to members (variables and methods) within the same class. However, it cannot be applied to class declarations.
C. Default: A class can be declared with the default access modifier in Java. If no access modifier is specified for a class, it is considered to have default access. This means that the class can be accessed within the same package but not from outside the package.
Therefore, the correct answer is B) Private. This option is incorrect because a class cannot be declared as private in Java.
Following code will result in: int a = 3.5;
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Compilation error
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Runtime error
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a being 3.5
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a being 3.
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;
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Compilation error
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Runtime error
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No errors
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;
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Compilation error: Divisions must be in a try block.
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Compilation error: DivideByZeroException
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Runtime Exception
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No Error: a is NaN
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;
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Compilation error: Divisions must be in a try block
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Compilation error: DivideByZeroException
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Runtime Exception
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No Error: a is NaN
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 because there is no requirement to enclose divisions in a try block. The try-catch block is used to handle exceptions, but it is not necessary for every division operation.
Option B) Compilation error: DivideByZeroException - This option is incorrect because there is no compilation error related to a divide-by-zero exception. In this case, a runtime exception will occur.
Option C) Runtime Exception - This option is correct. The division by zero operation is not allowed in mathematics, and it will result in a runtime exception called "ArithmeticException: Divide by zero". Therefore, executing the given code will result in a runtime exception.
Option D) No Error: a is NaN - This option is incorrect. NaN (Not a Number) is a special floating-point value that represents an undefined or unrepresentable result. However, dividing by zero does not result in NaN. It results in a runtime exception.
The correct answer is C. The code will result in a runtime exception.
Following code will result in: class A { int b = 1; public static void main(String [] args) { System.out.println("b is " + b); }}
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Compilation error
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Runtime Error
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Runtime Exception
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Output of b is 1
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 {}
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Compile error
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Runtime Exception
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No error
AI Explanation
To answer this question, we need to understand the concept of inheritance and object creation in Java.
In the given code, we have two classes: A and B. Class A has a main method, which is the entry point of the program. Inside the main method, a new object b is created of type B using the constructor new A().
Now let's go through each option to understand why it is correct or incorrect:
Option A) Compile error - This option is correct. The code will result in a compile error because we are trying to create an object of type B using the constructor of class A. Since class B extends class A, it is valid to create an object of type B using the constructor of class B, but not vice versa. Therefore, the code B b = new A(); will result in a compile error.
Option B) Runtime Exception - This option is incorrect. There will be no runtime exception because the code will not compile in the first place.
Option C) No error - This option is incorrect. There will be a compile error, as explained in option A.
The correct answer is A) Compile error. This option is correct because we are trying to create an object of type B using the constructor of class A, which is not allowed in Java.
Following code will result in: class A { public static void main(String [] args) {A a = new B(); }} class B extends A {}
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Compiler error
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Runtime Exception
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No errors
AI Explanation
To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) Compiler error - This option is incorrect because there are no syntax or compilation errors in the given code. The code compiles successfully.
Option B) Runtime Exception - This option is incorrect because there are no runtime exceptions thrown in the given code. The code executes without any errors.
Option C) No errors - This option is correct because there are no syntax errors or runtime exceptions in the given code. The code compiles successfully and executes without any issues.
The correct answer is C) No errors. This option is correct because the code is syntactically correct and executes without any errors.
Therefore, the code will result in no errors.