Create a generic array in Java

Create a generic array in Java

When using generics, I think plenty of people tried the following code, to create a generic array

T[] array = new T[];

When we write code compiler will report Cannot create a generic array of T, beginner when generics, see this mistake to think that Java can not create a generic array, with the continuous in-depth, when Tinking in Java generics see, Java is possible to create generic, really ignorant to limit their imagination.

Java, create a generic example:

Create a generic array of key classes

import java.lang.reflect.Array;

class GenericsArray {
    @SuppressWarnings({ "unchecked", "hiding" })
    public static <T>  T[] getArray(Class<T> componentType,int length) {
        return (T[]) Array.newInstance(componentType, length);
    }
}

Test category

import java.util.Arrays;

public class TestGenericArray {
    public static void main(String[] args) {
        @SuppressWarnings("static-access")
        Person[] persons = new GenericsArray().getArray(Person.class, 10);
        
        System.out.println(Arrays.toString(persons));
        for (int i = 0; i < persons.length; i++) {
            persons[i]=new Person(i);
        }
        System.out.println(Arrays.toString(persons));
    }
}

Person class

public class Person {
    private int id;
    public Person(int id) {
        this.id = id;
    }
    @Override
    public String toString() {
        return "Person [id=" + id + "]";
    }
}

Test Results