Java Constructors generally

Java Constructors generally

  • A constructor is a special method with the same name as its class and has no return.
  • A constructor is called by the Java system when a new class instance is created (an object).
  • This gives the class an opportunity to set up initials for use during the object's lifetime.
  • A constructor can accept arguments and can be overloaded as other methods.
  • Constructors are not, however, inherited or overrided like other methods.
  • The default constructor is the no-argument constructor automatically generated unless you define another constructor. However, if you define at least one constructor, the default constructor is not generated.
    Constructor example:
    public class Person {
      private int age;
      private String name="Nobody";
    // Constructor with two parameters
    // As this constructor is created - 
    // no default constructor will be generated  
      public Person(int age, String name) {
        this.age = age;
        this.name = name;
      }
    
      public int getAge() {
        return age;
      }
    
      public void setAge(int age) {
        this.age = age;
      }
    
      public String getName() {
        return name;
      }
    
      public void setName(String name) {
        this.name = name;
      }
       public static void main(String args[]) {
         Person ricard= new Person(23,"Ricard");
         System.out.println("First person is called "
                 +ricard.getName()+" and is "
                 +ricard.getAge()+" years");
       }
    }
    The result of this is:
    First person is called Ricard and is 23 years
    You can download this example here (needed tools can be found in the right menu on this page).
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