Java is one of the most popular programming languages in the world. It is used to develop web applications, mobile applications, and desktop applications. Java provides various built-in classes and methods that help developers to perform various operations efficiently. One of these classes is the NumberFormatException class. This class is used to handle invalid input in the form of integers. In this article, we will discuss Java lang NumberFormatException Invalid int code examples.
The NumberFormatException is a class that extends the RuntimeException class. It is thrown when an attempt is made to convert a string to a number format, but the string does not contain a valid number. This can happen when the string contains non-numeric characters or when the number is too large or too small to be represented by an integer.
Here are some code examples that demonstrate how to use the NumberFormatException class to handle invalid input in the form of integers.
Example 1: Handling non-numeric input
In this example, we have a string that contains non-numeric characters. When we try to convert the string to an integer using the parseInt() method, a NumberFormatException is thrown.
String str = "one";
try {
int num = Integer.parseInt(str);
System.out.println("Number = " + num);
} catch (NumberFormatException ex) {
System.out.println("Invalid input");
}
Output:
Invalid input
Example 2: Handling overflow
In this example, we have a string that represents a number that is too large to be represented by an integer. When we try to convert the string to an integer using the parseInt() method, a NumberFormatException is thrown.
String str = "2147483648";
try {
int num = Integer.parseInt(str);
System.out.println("Number = " + num);
} catch (NumberFormatException ex) {
System.out.println("Invalid input");
}
Output:
Invalid input
Example 3: Handling underflow
In this example, we have a string that represents a number that is too small to be represented by an integer. When we try to convert the string to an integer using the parseInt() method, a NumberFormatException is thrown.
String str = "-2147483649";
try {
int num = Integer.parseInt(str);
System.out.println("Number = " + num);
} catch (NumberFormatException ex) {
System.out.println("Invalid input");
}
Output:
Invalid input
In all the above examples, we are trying to convert a string to an integer using the parseInt() method. When the string does not contain a valid integer, a NumberFormatException is thrown. We then catch this exception and handle it appropriately.
There are other methods available in Java to convert a string to a number, such as parseShort(), parseLong(), parseFloat(), and parseDouble(). These methods also throw a NumberFormatException when an invalid input is encountered.
In conclusion, the NumberFormatException class is a powerful tool for handling invalid input in the form of integers. By using this class, developers can build robust applications that can handle unexpected input and recover gracefully. It is important for Java developers to understand how and when to use this class to ensure that their applications are reliable and error-free.
I will provide more information about the previous topics covered in the article.
Firstly, let's discuss the parseInt() method, which is used in all the examples provided above. The parseInt() method is a static method that is defined in the Integer class. This method takes a string as an argument and tries to convert it to an integer. If the conversion is successful, it returns the integer value. However, if the string does not contain a valid integer, a NumberFormatException is thrown. Here is the syntax of the parseInt() method:
public static int parseInt(String s) throws NumberFormatException
The parseInt() method takes a single argument, which is a string that represents the integer to be parsed. This method returns an integer value that is represented by the string. If the string cannot be parsed, a NumberFormatException is thrown.
The NumberFormatException class, as mentioned earlier, is a subclass of the RuntimeException class. This class represents an exception that occurs when an attempt is made to convert a string to a numeric format, but the string does not contain a valid number. Here is the syntax of the NumberFormatException class:
public class NumberFormatException extends RuntimeException
The NumberFormatException class has a single constructor that takes an optional error message as an argument. The error message is used to describe the reason for the exception.
Now let's talk about the examples provided in the article. In the first example, we tried to convert a string "one" to an integer using the parseInt() method. As the string does not contain a valid number, a NumberFormatException is thrown. We then catch this exception and print "Invalid input".
In the second example, we tried to convert a string "2147483648" to an integer using the parseInt() method. This number is too large to be represented by a 32-bit integer, and hence a NumberFormatException is thrown. We then catch this exception and print "Invalid input".
In the third example, we tried to convert a string "-2147483649" to an integer using the parseInt() method. This number is too small to be represented by a 32-bit integer, and hence a NumberFormatException is thrown. We then catch this exception and print "Invalid input".
In all the examples, we caught the NumberFormatException and handled it appropriately by printing an error message. It is important to handle this exception in your code to avoid unexpected behavior or unexpected termination of the program.
To summarize, the NumberFormatException is a class that is used to handle invalid input in the form of integers. This class is thrown when an attempt is made to convert a string to a number format, but the string does not contain a valid number. The parseInt() method is used to convert a string to an integer, and if the string does not contain a valid integer, a NumberFormatException is thrown. It is important for Java developers to understand these concepts and use them appropriately in their code to ensure that their applications are robust and error-free.
Popular questions
Sure, here are five questions with answers related to Java lang NumberFormatException Invalid int code examples:
-
What is NumberFormatException in Java?
Ans: NumberFormatException is a subclass of RuntimeException that occurs when an attempt is made to convert a string to a numeric format, but the string does not contain a valid number. -
What is the parseInt() method used for in Java?
Ans: The parseInt() method is used to convert a string to an integer in Java. If the string does not contain a valid integer, a NumberFormatException is thrown. -
What happens if a string that contains non-numeric characters is passed to the parseInt() method in Java?
Ans: When a string that contains non-numeric characters is passed to the parseInt() method, it throws a NumberFormatException. -
How can we handle the NumberFormatException in Java?
Ans: We can handle the NumberFormatException in Java by using a try-catch block. When an exception occurs, we catch it and handle it appropriately. -
Give an example where NumberFormatException is thrown in Java due to overflow.
Ans: An example where NumberFormatException is thrown in Java due to overflow is when we try to convert a string "2147483648" to an integer using the parseInt() method. This number is too large to be represented by a 32-bit integer, and hence a NumberFormatException is thrown.
Tag
NumberFormatException.
