This is an example of how to use a generic constructor of a class. In order to see how a generic constructor works we have created a class with a generic constructor and then created instances of the class to use its constructor.
GenericClassclass has a double field, val.- It has a constructor using an object of
Tclass that extendsNumber, sets its double field to the object’s double value, usingdoubleValue()API method of Number and returns the object. - It has a method
void value()that prints the double field of the class. - We create a new instance of GenericClass with a given Integer object and another instance of
GenericClasswith a given Float object, and call values() method for both objects. - In both cases the double value of the fields are returned.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
class GenericClass {
private double val;
<T extends Number> GenericClass(T arg) {
val = arg.doubleValue();
}
void values() {
System.out.println("val: " + val);
}
}
public class GenericConstructor {
public static void main(String args[]) {
GenericClass c1 = new GenericClass(100);
GenericClass c2 = new GenericClass(123.5F);
c1.values();
c2.values();
}
}
Output:
val: 100.0
val: 123.5
This was an example of how to use a generic constructor of a class in Java.
