@Override above the method

Week 5: Class hierarchies/12A. Object-class methods - toString()

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+Since all Java classes directly or indirectly inherit the Object class, all classes also inherit methods in the 'Object' class. 
+The METHODS of the Object class are special in that they are USU INTENDED TO BE OVERWRITTEN in 
+the inheriting classes - the basic functionality defined in the Object class is almost never sufficient. 
+
+In this section, let's look at a few methods found in the Object class and their sensible reimplementation.
+
+
+
+
+
+========================================================================
+
+
+Method toString
+The toString() method, inherited from the Object class, is intended for situations where you want to 
+represent the CONTENTS of a class as a STRING. 
+For example, the print and println print methods can automatically call the toString() method of an object when the object is printed.
+
+The default implementation of the method prints the CLASS NAME and the HASH CODE of the CLASS, separated by an @ sign. For example:
+
+ 
+
+class Person {
+    protected String name;
+    protected String email;
+    
+    public Person(String name, String email) {
+        this.name = name;
+        this.email = email; 
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.nimi = name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }  
+}
+
+public class PersonTest {
+    public static void main(String[] args) {
+        Person p = new Person("Pat Person", "[email protected]");
+        System.out.println(p);  
+    }
+}
+
+Program outputs (for example)
+Person@372f7a8d
+ 
+
+
+
+
+========================================================================
+
+
+Let's define the toString method for the Student class 
+so that it returns the data content in a more sensible format. 
+The method now also uses the @Override annotation. 
+It does not actually affect the execution of the program, but it ***tells Java that the method is to be overwritten***. 
+So, for example, if there is a misspelling in the name (say, toStrnig or tostring), Java will catch it at compile time.
+
+class Person {
+    protected String name;
+    protected String email;
+    
+    public Person(String name, String email) {
+        this.name = name;
+        this.email = email; 
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }  
+    
+    @Override
+    public String toString() {
+        return this.name + ", email: " + this.email;
+    }
+}
+
+
+Now when the Person object is printed, Java automatically calls the toString method. 
+Note that the toString method can of course also be called by itself, 
+for example when you want to store the string it returns in a variable. 
+
+Also, PRINTING A LIST AUTOmatically CALLS the toString method on all elements of the list.
+
+public static void main(String[] args) {
+    Person p = new Person("Pat Person", "[email protected]");
+    // 1
+    // print the object
+    System.out.println(p);        
+    
+    Person p2 = new Person("Paula Personnel", "[email protected]");
+    Person p3 = new Person("Pete Personification", "[email protected]");
+
+
+    
+    // 2
+    // print the object toString
+    String pat = "Here's person: " + p.toString();
+    System.out.println(pat);
+
+
+    // 3
+    //print the list of objects
+    ArrayList<Person> persons = new ArrayList<>();
+    persons.add(p);
+    persons.add(p2);
+    persons.add(p3);
+    System.out.println(persons);
+}
+
+Program outputs:
+Pat Person, email: [email protected]
+Here's person: Pat Person, email: [email protected]
+[Pat Person, email: [email protected],
+Paula Personnel, email: [email protected],
+Pete Personification, email: [email protected]]
+
+