In Java, a parameterized constructor is a constructor that takes one or more parameters. It is used to initialize the instance variables of an object with the values passed as arguments to the constructor.

Here's an example of a parameterized constructor:

public class MyClass {
    private int value;

    public MyClass(int value) {
        this.value = value;
    }

    public int getValue() {
        return value;
    }
}

In this example, we have a class called MyClass with a single field value, and a parameterized constructor that takes an integer value and sets the value of the value field to the value passed as an argument. To create an object of MyClass using this constructor, we can use the following code:

MyClass myObj = new MyClass(10);

This will create a new instance of MyClass, with the value field set to 10.