CODEWITHSUNDEEP
javaclass
thatsimplekid
thatsimplekid

Reputation: 39

Creating an instance of a class in Java?

In Java, I am trying to create an instance of a class that gets passed as a parameter. For instance:

public Class<? extends superclass> theClass;

public constructor(Class<? extends superclass> myClass){
    this.theClass = myClass;
}

public superclass getInstance(){
    return < AN INSTANCE OF theClass >
}

I do not know how I would create an instance of theClass... Is this possible, or will I need to find another way of doing it?

Any help is much appreciated.

Upvotes: 1

Views: 108

Answers (2)

T.J. Crowder
T.J. Crowder

Reputation: 1074138

Yes, it's possible:

return this.theClass.newInstance();

More in java.lang.Class and java.lang.reflect, including a way to find other constructors that the class may have and a means of calling them with arguments.

For instance, suppose you know you need to call a constructor that accepts a String argument. You can use getConstructor to locate that constructor:

Constructor ctor = this.theClass.getConstructor(String.class);

...and then call it

return ctor.newInstance("the string");

Upvotes: 2

M A
M A

Reputation: 72844

You can call Class#newInstance():

public Superclass getInstance() throws InstantiationException, IllegalAccessException {
    return theClass.newInstance();
}

From the Javadocs:

Creates a new instance of the class represented by this Class object. The class is instantiated as if by a new expression with an empty argument list. The class is initialized if it has not already been initialized.

Upvotes: 2

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