Java Throws Keyword

Java Throws Keyword

Introduction:
In Java, the throws keyword is used to declare that a method may throw one or more specific checked exceptions during its execution. When a method is likely to encounter a checked exception, it must either handle the exception using a try-catch block or propagate it further using the throws keyword in its method signature.

Syntax:

java
returnType methodName(parameterList) throws ExceptionType1, ExceptionType2, ... {
    // Method code that may throw exceptions
}

Explanation:

• returnType: The data type of the value returned by the method.
• methodName: The name of the method.
• parameterList: The list of input parameters the method may accept.
• ExceptionType1, ExceptionType2, ...: The list of exception types that the method may throw. These should be checked exceptions or subclasses of Exception.

Example:
Let's create an example to demonstrate the use of the throws keyword:

java
import java.io.FileReader;
import java.io.IOException;

public class FileHandler {

    public String readFile(String fileName) throws IOException {
        FileReader fileReader = null;
        StringBuilder content = new StringBuilder();

        try {
            fileReader = new FileReader(fileName);
            int charValue;
            while ((charValue = fileReader.read()) != -1) {
                content.append((char) charValue);
            }
        } finally {
            if (fileReader != null) {
                fileReader.close();
            }
        }

        return content.toString();
    }
}

Explanation:
In this example, we have a class FileHandler with a method readFile that reads the content of a file specified by fileName. The method uses a FileReader to read the file content character by character and appends it to a StringBuilder. Since the FileReader can throw a checked IOException, we use the throws keyword to declare that the readFile method may throw this exception.

Now, when another method or code calls the readFile method, it must handle the IOException using a try-catch block or declare the IOException in its own method signature using the throws keyword.

Conclusion:
The throws keyword in Java is essential for declaring and handling checked exceptions in methods. By using this keyword, we can specify the types of exceptions that might be thrown during the execution of the method, enabling proper handling and ensuring robustness in the code.