PS C:\Code> javac GenericNodeTester.java
GenericNodeTester.java:5: error: incompatible types: double cannot be converted to Integer
    GenericNode<Integer> nodeA = new GenericNode<Integer>( 5.5 );

Class Bird

The generic class GenericNode can be used with your own classes.

Say that you are a birdwatcher and wish to keep track of the different species of birds you have seen. Here is a class you might use. (A better class would have much more in it.)

public class Bird
{
  String genus;
  String species;
  String commonName;
  int sightings;
  
  public Bird( String genus, String species, String commonName, int sightings)
  {
    this.genus = genus;
    this.species = species;
    this.commonName = commonName;
    this.sightings = sightings;
  }
  
  public incSightings()
  {
    sightings++ ;
  }
  
  public String toString()
  {
    return genus + " " + species + " (" + commonName + ") seen:" + sightings; 
  }
} 

The tester class uses GenericNode for this user-designed class:

public class GenericNodeTester
{
  public static void main (String args[])
  {
    Bird robin = new Bird("Turdus", "migratoris", "Robin", 1 );
    GenericNode<Bird> node = new GenericNode<Bird>( robin );
    System.out.println("node: " + node );
    node.getValue().incSightings();    
    System.out.println("node: " + node );
  }
} 

Source files for all three classes should be in the same subdirectory:

PS C:\Code> javac GenericNodeTester.java
PS C:\Code> java GenericNodeTester
node: Turdus migratoris (Robin) seen:1
node: Turdus migratoris (Robin) seen:2