How Can I Prevent NumberFormatException When Parsing Non-Integer Strings in Java?

Preventing NumberFormatException for Non-Integers

When processing numerical data, it's crucial to handle situations where the expected numerical value is missing or non-numeric. In Java, the NumberFormatException occurs when trying to parse a non-numerical string to an integer.

Consider the following scenario:

java.lang.NumberFormatException: For input string: "N/A"
...

This exception indicates that the string "N/A" cannot be interpreted as an integer. To prevent this, there are two main strategies:

Exception Handling

In this approach, we explicitly check for potential non-numerical values before attempting to parse the string:

try {
    int i = Integer.parseInt(input);
} catch (NumberFormatException ex) {
    // Handle the exception (e.g., log error, provide user feedback)
}

If the string is non-numeric, the exception block will be executed, allowing you to handle the situation gracefully.

Pattern Matching

Alternatively, we can use Java's regular expression capabilities to verify whether the string matches the expected integer format:

String input = ...;
String pattern = "-?\d+";
if (input.matches(pattern)) {
    // The string is an integer
} else {
    // The string is not an integer
}

The pattern "-?d " matches any positive or negative integer, ensuring that we only proceed with parsing if the string is valid.

By applying either method, you can prevent the NumberFormatException and ensure that your code handles non-numeric values appropriately.

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