For arrays only, JDK 12 provides the Class<?> componentType() method. This method returns the component type of the array, as shown in the following two examples:

Pair[] pairs = new Pair[10];
String[] strings = new String[] {"1", "2", "3"};

// class modern.challenge.Pair
System.out.println("Component type of Pair[]: " 
  + pairs.getClass().componentType());

// class java.lang.String
System.out.println("Component type of String[]: " 
  + strings.getClass().componentType());