Object in java

In Java, an object is an instance of a class. When a class is instantiated, one or more objects are created in memory that have the same properties and behavior as the class.

Here is an example of creating and using objects in Java:

                
    public class Person {
        private String name;
        private int age;

        public Person(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public void sayHello() {
            System.out.println("Hello, my name is " + name);
        }
    }

    public class Main {
        public static void main(String[] args) {
            Person john = new Person("John", 30);
            john.sayHello();
            System.out.println(john.getName() + " is " + john.getAge() + " years old.");
            john.setAge(31);
            System.out.println(john.getName() + " is now " + john.getAge() + " years old.");
        }
    }

In this example, we have a Person class with a constructor that takes a name and age as parameters and sets the corresponding fields, as well as getter and setter methods for the name and age fields, and a sayHello() method that prints a message to the console.

In the Main class, we create a Person object named john by calling the constructor with the arguments "John" and 30. We then call the sayHello() method on john, and print out his name and age using the getName() and getAge() methods. We also modify the age field using the setAge() method, and print out the updated age.

The output of running this program would be:

                
    Hello, my name is John
    John is 30 years old.
    John is now 31 years old.

In summary, an object is an instance of a class in Java that has the same properties and behavior as the class. Objects are created by instantiating a class using the new keyword, and can be used to call the methods and access the fields of the class.

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