How to Identify Primitive Values in an Object[] Array?

Determining if an Object is Primitive

Question:
When dealing with an Object[] array, how can you identify which elements represent primitive values? Using Class.isPrimitive() appears to yield incorrect results.

Answer:
Understanding that the elements in an Object[] array are references to objects, it becomes clear that Class.isPrimitive() will always return false. To determine if an object is a "wrapper for primitive" (e.g., Integer for int), a custom approach is necessary.

Here's a Java code snippet that demonstrates a solution:

<code class="java">import java.util.*;

public class Test {

    public static void main(String[] args) {
        System.out.println(isWrapperType(String.class)); // false
        System.out.println(isWrapperType(Integer.class)); // true
    }

    private static final Set<Class<?>> WRAPPER_TYPES = getWrapperTypes();

    public static boolean isWrapperType(Class<?> clazz) {
        return WRAPPER_TYPES.contains(clazz);
    }

    private static Set<Class<?>> getWrapperTypes() {
        Set<Class<?>> ret = new HashSet<>();
        ret.add(Boolean.class);
        ret.add(Character.class);
        ret.add(Byte.class);
        ret.add(Short.class);
        ret.add(Integer.class);
        ret.add(Long.class);
        ret.add(Float.class);
        ret.add(Double.class);
        ret.add(Void.class);
        return ret;
    }
}</code>

By utilizing this approach, you can accurately determine whether an object in an Object[] array represents a primitive value or a wrapper class for a primitive value.

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