Test: Methods in Java - 2 - EmSAT Achieve MCQ

In Java, when a method is called with call by value, a copy of the variable's value is passed to the method. Any modifications made to the parameter within the method do not affect the original variable. Call by reference, on the other hand, passes the actual variable itself, allowing modifications to affect the original variable.

Recursive methods in Java can call themselves directly or indirectly. However, without proper termination conditions (base cases), recursive calls can lead to an infinite loop and cause a stack overflow error.

The 'modify' method takes an integer as a parameter, adds 5 to it, and returns the modified value. In the 'main' method, the variable 'x' is assigned the value 10. When 'modify' is called with 'x' as an argument, 'x' itself is not modified, but the modified value (15) is returned and assigned to 'y'. The sum of 'x' (10) and 'y' (15) is 25, which is printed.

Method hiding in Java occurs when a subclass defines a static method with the same signature as a static method in its superclass. The static method in the subclass "hides" the static method in the superclass.

Method overloading resolution in Java is the process of determining which method to call when multiple methods with the same name but different parameter lists are available. The compiler matches the arguments provided during the method call with the method's parameter types to determine the most appropriate method to invoke.

The 'swap' method takes two integers as parameters and swaps their values using a temporary variable. In the 'main' method, the variables 'x' and 'y' are passed to the 'swap' method. However, the method operates on copies of the variables, so the original values of 'x' and 'y' remain unchanged.

In Java, a method declaration specifies the method's return type, name, and parameter list, while a method definition includes the implementation of the method, including the method body.

In Java, a method can have multiple return statements. Multiple return statements allow flexibility in implementing conditional logic, where different values are returned based on different conditions.

The 'multiply' method is a recursive method that calculates the product of two numbers 'a' and 'b' using addition. If 'b' is 0, the method returns 0 (base case). Otherwise, it recursively calls itself with 'a' and 'b-1' as arguments, and the result is added to 'a'. The recursion continues until 'b' becomes 0.

Method overloading in Java occurs when a class has multiple methods with the same name but different parameter lists. Method overriding occurs when a subclass provides its own implementation of a method that is already defined in its superclass, using the same method name and parameter list.

A method in Java can have multiple return statements. The return statement is used to return a value from the method and terminate its execution.

The "static" keyword in a Java method declaration allows the method to be called without creating an instance of the class. Static methods belong to the class itself rather than individual instances of the class.

In Java, objects are always passed by value. When an object is passed as an argument to a method, a copy of the reference to the object is passed by value. This means that changes made to the object within the method are reflected outside the method.

The missing access modifier in option d) makes the method invalid. In Java, methods should have an access modifier (e.g., public, private, protected) specified explicitly.

Method overloading in Java involves defining multiple methods with the same name but different parameters. The parameters can differ in terms of number, types, or order.

The 'multiply' method in the code snippet takes two integer parameters and returns their product. In the 'main' 'method, 'multiply(3, 4)' is called, and the returned value, 12, is printed.

The 'updateString' method in the code snippet takes a string parameter and concatenates " World" to it. However, the concatenation is performed on a copy of the reference to the original string. Hence, the modification is not reflected outside the method, and the output remains "Hello."

The 'updateValue' method in the code snippet takes an integer parameter and increments it by 1. However, the parameter 'value' is a copy of the value of 'x' in the main method. Therefore, modifying 'value' does not affect the original variable 'x'.

The 'sum' method in the code snippet is overloaded with two versions: one that takes two integers and another that takes two doubles. In the 'main' method, 'sum(3, 4)' is called, and since the arguments are integers, the first version of 'sum' is invoked, returning the sum of 3 and 4, which is 7.

Both option a) and b) are valid methods to calculate the factorial of a number. The return type of the factorial function can be either 'int' or 'long' depending on the range of values you want to support.

Note: The other options c) and d) are not suitable for calculating the factorial. Option c) includes an extra parameter m that is not required for factorial calculation, and option d) takes an array as a parameter, which is not necessary for the factorial computation.