How to Use the super Keyword to Call a Base Class Constructor in Java

See Java: Tips and Tricks for similar articles.
Looking to improve your Java skills? Check out Webucator’s Java classes.

A derived Java class can call a constructor in its base class using the super keyword. In fact, a constructor in the derived class must call the super's constructor unless default constructors are in place for both classes.

To understand how to use the super keyword to call a base class constructor, follow these 10 steps.

  1. Open your text editor and type in the following Java statements: Java Source for super Class The program defines two properties, firstName and lastName. Notice that the program follows the Javabean specification for defining a property, i.e., a private variable with getter and setter methods. Also note that the constructor requires two parameters, the first name and the last name.
  2. Save your file as Person.java.
  3. Open a command prompt and navigate to the directory containing your Java program. Then type in the command to compile the source and hit Enter. Compile Source for super Class
  4. Create a new file in your text editor. Type in the following Java statements: Java Source for Derived class The Employee class defines one property, empId. This property will contain the employee ID. Notice that the constructor in this class calls the constructor in the super class (Person). The first name and last name parameters are passed to the constructor.
  5. Save your file as Employee.java.
  6. Return to the command prompt. Then type in the command to compile the source and hit Enter. Compile Source for Derived Class
  7. Now you will create an application to test your derived class. Create a new file in your text editor and type in the following Java statements: Java Source for Tester Class The program instantiates an Employee object and then calls the getFirstName and getLastName methods. The first name and last name parameters have been passed to the base constructor by the derived class constructor. The program also calls the getEmpId method in the Employee object.
  8. Save your file as UsesuperKeywordToCallBaseConstructor.java.
  9. Return to the command prompt. Then type in the command to compile the source and hit Enter. Compile Source for Tester Class
  10. You will now test your program. Type in the command to run the Java runtime launcher and then hit Enter. Run Tester for Derived Class Notice the output of the program verifies that the first name and the last name were successfully passed to the base class constructor by the Employee constructor.

Related Articles

  1. How to Check Object Type in Java
  2. How to Create a Jar File in Java
  3. How to Compile Packages in Java
  4. How to Throw an Exception in Java
  5. How to Create an Exception Class in Java
  6. How to Use the super Keyword to Call a Base Class Constructor in Java (this article)
  7. How to Use the Comparator.comparing Method in Java 8
  8. How to Use System.in in Java
  9. How to Call an Interface Method in Java
  10. How to Add a Time Zone in the Java 8 Date/Time API
  11. How to Rethrow an Exception in Java
  12. How to Use the instanceof Operator with a Generic Class in Java
  13. How to Instantiate an Object in Java
  14. How to Filter Distinct Elements from a Collection in Java 8
  15. How to Create a Derived Class in Java
  16. How to Skip Elements with the Skip Method in Java 8
  17. How to Create a Java Bean
  18. How to Implement an Interface in Java
  19. How to Compare Two Objects with the equals Method in Java
  20. How to Set PATH from JAVA_HOME
  21. How to Prevent Race Conditions in Java 8
  22. How to Write a Block of Code in Java
  23. How to Display the Contents of a Directory in Java
  24. How to Group and Partition Collectors in Java 8
  25. How to Create a Reference to an Object in Java
  26. How to Reduce the Size of the Stream with the Limit Method in Java 8
  27. How to Write an Arithmetic Expression in Java
  28. How to Format Date and Time in the Java 8 Date/Time API
  29. How to Use Comparable and Comparator in Java
  30. How to Break a Loop in Java
  31. How to Use the this Keyword to Call Another Constructor in Java
  32. How to Write a Unit Test in Java
  33. How to Declare Variables in Java
  34. How to Override Base Class Methods with Derived Class Methods in Java
  35. How to Use Serialized Objects in Java
  36. How to Write Comments in Java
  37. How to Implement Functional Interfaces in Java 8
  38. How to Write Type Parameters with Multiple Bounds in Java
  39. How to Add Type and Repeating Annotations to Code in Java 8
  40. How to Use Basic Generics Syntax in Java
  41. How to Map Elements Using the Map Method in Java 8
  42. How to Work with Properties in Java
  43. How to Write while and do while Loops in Java
  44. How to Use the finally Block in Java
  45. How to Write for-each Loops in Java
  46. How to Create a Method in Java
  47. How to Continue a Loop in Java
  48. How to Handle Java Files with Streams
  49. How to Create an Interface Definition in Java
  50. How Default Base Class Constructors Are Used with Inheritance