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Java null check

Problem:

How to do null check in Java? The old way was to do validation manually, but since Java 7 there’s a better way. In the following example we show the difference.

Solution:

In the below Java example we show how to validate method arguments in the old and the new way. Since Java 7 there’s java.util.Objects class with a couple of helper methods that ease working with objects (see Objects equals hascode example). Here we use requireNotNull(Object,String) that will handle NullPointerException creation for us and will make the code cleaner:

package com.farenda.java.util;

import java.util.Objects;

public class ObjectsRequireNotNull {

    private static void theOldWay(String data) {
        System.out.println("\nOld, verbose way of checking arguments:");
        if (data == null) {
            throw new NullPointerException("'data' must not be null");
        }

        System.out.println("Processing data: " + data);
    }

    private static void theNewWay(String data) {
        System.out.println("\nThe new, Java 7 way of checking arguments:");
        Objects.requireNonNull(data, "'data' must not be null");

        System.out.println("Processing data: " + data);
    }

    public static void main(String[] args) {
        try {
            theOldWay("Hello world!");
            theOldWay(null);
        } catch (NullPointerException e) {
            System.out.println("Caught: " + e.getMessage());
        }

        try {
            theNewWay("Hello world!");
            theNewWay(null);
        } catch (NullPointerException e) {
            System.out.println("Caught: " + e.getMessage());
        }
    }
}

And here’s the result of running the example:

Old, verbose way of checking arguments:
Processing data: Hello world!

Old, verbose way of checking arguments:
Caught: 'data' must not be null

The new, Java 7 way of checking arguments:
Processing data: Hello world!

The new, Java 7 way of checking arguments:
Caught: 'data' must not be null

As you can see the results are the same, but the code in theNewWay() method is cleaner. Unfortunately, there is no method that would take any predicate and throw IllegalArgumentException in case of it not being satisfied. Maybe in some further Java version. :-)

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