How is method overloading resolved when there is an ambiguity in method signatures?
- The JVM randomly selects one of the overloaded methods.
- The compiler throws an error and asks for explicit casting of parameters.
- The method with the least specific parameter types is chosen.
- The method with the most specific parameter types is chosen.
In Java, when there is an ambiguity in method signatures during method overloading, the compiler chooses the method with the most specific parameter types. Specificity is determined by the inheritance hierarchy, with the most specific type being favored. This ensures that the correct method is called based on the arguments provided.
Which of the following loops will always execute its code block at least once?
- do-while loop
- for loop
- if statement
- while loop
The do-while loop is designed to execute its code block at least once, as it checks the condition after executing the loop body. This is useful when you want to ensure that a piece of code runs before checking the condition for termination.
The method ________ of FileOutputStream class is used to write a specific byte of data to a file output stream.
- append
- write
- writeByte
- writeData
The write method of the FileOutputStream class is used to write a specific byte of data to a file output stream. You can use this method to write individual bytes or byte arrays to a file.
What is the default constructor in Java?
- A constructor provided by Java for every class
- A constructor with a single parameter
- A constructor with default values
- A constructor with no parameters
In Java, the default constructor is a constructor provided by Java for every class that doesn't explicitly define its own constructor. It takes no parameters and initializes instance variables to their default values. The other options do not accurately describe the default constructor in Java.
Imagine a scenario where you are developing a library, and you want to restrict the usage of some specific methods to the external world but allow them to be used inside the package. How would you implement this using access modifiers?
- package-private
- private
- protected
- public
To restrict the usage of certain methods to the external world while allowing them to be used within the package, you would use the package-private access modifier. This is achieved by not specifying any access modifier (default) before the method declaration. Public methods are accessible from anywhere, private methods are restricted to the class, and protected methods allow access within the package and subclasses.
Why does Java not support operator overloading?
- Because it's not feasible to implement
- To avoid ambiguity in code
- To promote method overloading instead
- To simplify the language and reduce complexity
Java does not support operator overloading primarily to simplify the language and reduce complexity. Operator overloading can lead to ambiguity in code, making it harder to read and maintain. Instead, Java encourages method overloading as a way to achieve similar functionality.
________ collection classes store objects, whereas ________ collection classes store primitive data types.
- ArrayList / LinkedList
- HashMap / HashSet
- Vector / Hashtable
- Wrapper / Primitive
Wrapper collection classes (such as ArrayList) store objects, while Primitive collection classes (such as ArrayList) store primitive data types directly. The wrapper classes allow primitive data types to be used in collections that require objects.
What will happen if you try to assign a value larger than the maximum value of the byte data type to a byte variable?
- A compilation error will occur because it's not possible to assign a larger value.
- An exception will be thrown at runtime.
- The byte variable will automatically promote to a larger data type to accommodate the value.
- The value will be truncated to fit within the range of the byte data type.
In Java, if you try to assign a value larger than the maximum value (127) of the byte data type to a byte variable, the value will be truncated, and the least significant bits will be retained. This is known as "overflow." The other options do not accurately describe the behavior of byte variables.
How can you efficiently represent sparse matrices using multi-dimensional arrays in Java?
- Use a hashmap to store non-empty elements with keys representing row and column indices for fast retrieval.
- Use a linked list of linked lists to represent rows and columns, only storing non-empty elements.
- Use a one-dimensional array to store non-empty values along with their row and column indices for efficient access.
- Use a two-dimensional array with default values set to null or another sentinel value to represent empty elements.
To efficiently represent sparse matrices in Java, you can use a one-dimensional array to store non-empty values along with their row and column indices. This approach minimizes memory usage and provides fast access to non-empty elements. The other options do not efficiently address the issue of sparse matrices.
Which of the following data types can store a null value in Java?
- Integer
- String
- double
- int
In Java, only reference data types (objects) can store a null value. Among the given options, String is a reference data type that can store null. The other options are primitive data types and cannot hold null values.