Which method is used to add an element to an ArrayList?
- add()
- append()
- insert()
- push()
The add() method is used to add an element to an ArrayList in Java. It appends the specified element to the end of the list. Other methods like insert(), append(), and push() are not used for adding elements to ArrayLists.
Which of the following statements correctly creates an object of a class named 'Dog'?
- Dog dog = new Dog();
- Dog obj = createObject();
- Dog.create();
- Dog.new();
To create an object of a class named 'Dog' in Java, you should use the class name followed by the constructor using the new keyword, like this: Dog dog = new Dog();. The other options are not the correct way to create an object of a class in Java.
To write a newline character when using FileWriter, you can use ________.
- "n"
- "n"
- "r"
- 'n'
To write a newline character when using FileWriter, you can use "n". This escape sequence represents a newline character in Java and is commonly used to create line breaks in text files.
Which method is used to retrieve the protocol type of a URL in Java?
- fetchProtocol()
- getProtocol()
- getURLProtocol()
- retrieveProtocol()
In Java, to retrieve the protocol type of a URL, you should use the getProtocol() method of the URL class. It returns a String containing the protocol, such as "http," "https," "ftp," etc. The other options do not exist as valid methods for this purpose.
Can we overload the "+" operator to concatenate two strings and add two integers in a custom class?
- No, Java does not support operator overloading.
- Yes, by defining a method named + in the custom class.
- Yes, by defining methods named add and concatenate for the custom class.
- Yes, by using the + operator with different parameter types in the method definition.
No, Java does not support operator overloading. In Java, the + operator is not overloaded for user-defined classes. The + operator is only used for addition when applied to numeric data types and for string concatenation when used with strings. Therefore, you cannot define custom behavior for the + operator in user-defined classes.
Does Java support operator overloading?
- No, not at all.
- Only for arithmetic ops.
- Yes, for all operators.
- Yes, for selected ops.
Java does not support operator overloading for custom classes. While some languages do allow operator overloading, Java enforces a fixed set of operators for built-in types, and you cannot create custom operator overloads. This limitation helps maintain code readability and prevents ambiguity.
How can we handle SQL exceptions that may occur during the execution of a JDBC program?
- Ignore them and let the program continue
- Use assert statements to handle exceptions
- Use if-else statements to handle exceptions
- Use try-catch blocks to catch and handle exceptions
SQL exceptions in a JDBC program should be handled using try-catch blocks. Ignoring them can lead to unexpected program behavior, and try-catch allows you to gracefully handle errors, log them, or take corrective actions. The other options are not recommended approaches for handling exceptions in JDBC.
To write primitive data types like int or double to a file in a machine-independent way, you might use ________.
- DataOutputStream
- FileInputStream
- ObjectInputStream
- ObjectOutputStream
To write primitive data types to a file in a machine-independent way, you can use DataOutputStream. It provides methods for writing different data types to a file while ensuring that the data can be read back correctly.
How does Java handle the division of an integer by zero?
- It returns NaN (Not-a-Number).
- It returns a positive or negative infinity value, depending on the sign of the numerator.
- It returns zero.
- It throws an ArithmeticException.
In Java, dividing an integer by zero results in an ArithmeticException being thrown at runtime. Division by zero is mathematically undefined, and Java handles it by throwing this exception to indicate the error. Options 1, 3, and 4 are incorrect because they don't accurately represent how Java handles this situation.
A JDBC ________ provides the necessary methods to interact with the database.
- Connection
- Driver
- ResultSet
- Statement
In JDBC, a Connection is used to establish a connection to a database. It provides the necessary methods to interact with the database, such as executing SQL queries and managing transactions. A JDBC Driver is responsible for establishing the connection, but the Connection object is what allows you to interact with the database.