Create Object of new different Class every time

Question

I want to create objects of a new class(different name specifically) continuously.

public static void main(String args[]) {
    while (true) {
        Object obj = getNewClassObject();
        System.out.println(obj.getClass.getName());
    }
}

public static Object getNewClassObject() {
    // some code
}

The task is what should we write in the method so it returns an Object of different class every time and the program prints different class name in each line.

I have tried using Anonymous class, Inner class, lambdas etc.. but they all return the same class name. My current "lame" solution is creating new class files inside a play application(has reloading ability) and then using reflection lib(or just java code) to load class and get the object of the new class.

But it takes a lot of memory also reflection method getSubTypeOf() takes a lot of time ~100 secs and after some time I get OutOfMemoryError. I hope there is a better way to do it. I am thinking something like unloading or releasing class metadata to free up memory.

Dmytro Mitin · Accepted Answer · 2020-09-14T08:44:52.447

With Javassist try

private static ClassPool pool = ClassPool.getDefault();
private static RandomString rs = new RandomString();

public static Object getNewClassObject() {
    String name = rs.nextString();
    Object obj = null;

    try {
        obj = pool.makeClass(name).toClass().newInstance();
    } catch (Exception e) {
        throw new RuntimeException(e);
    }

    return obj;
}

RandomString is from here: How to generate a random alpha-numeric string?

pom.xml

<dependency>
    <groupId>org.javassist</groupId>
    <artifactId>javassist</artifactId>
    <version>3.27.0-GA</version>
</dependency>

yes, this worked. so simple and elegant. Thank you so much. – sridhar vaishnava Sep 11 '20 at 23:15 — sridhar vaishnava, Sep 11 '20 at 23:15

Create Object of new different Class every time

1 Answers1