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Java Object getClass()
What is a Object in Java?
In Java, an object is an instance of a class. A class is a blueprint or template that defines the properties and methods of an object. An object is created from a class and can be used to access the properties and methods of that class.
- An object in Java is created using the new keyword, followed by the class name and constructor.
To know more about Object toString in java read the complete article.
Object getClass() method.
In Java, the getClass() method is a method that is defined in the Object class, which is the parent class of all classes in Java. It returns the Class object that represents the runtime class of the object on which the method is called.
- The Class object returned by the getClass() method provides information about the class, such as its fully qualified name, its constructors, methods, and fields. It also provides methods to perform reflection on the class, such as creating new instances of the class, invoking methods, and accessing fields.
Returns
The Class object that represents the runtime class of this object.
Note:
The general form of getClass() method is public final Class getClass().
Syntax:
public final Class<?> getClass()
Parameters:
The getClass() method does not take any parameters.
Let’s look at a object-related Java program where the Java object getClass Method is used to perform an operation on the given object.
Example: Java Object getClass() Method
Run
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
}
public class Main {
public static void main(String[] args) {
Person person = new Person("John", 30);
Class c = person.getClass();
System.out.println("Class Name: " + c.getName());
}
}
Output
Class Name: Person
Explanation:
In this example, the Person class has two fields, name and age, and a constructor that initializes these fields. The main class creates an instance of the Person class, person and it calls the getClass() method on the object which returns a Class object representing the runtime class of the object.
Then, it calls the getName() method on the class object which returns the fully qualified name of the class.
Example 2 : Java object getClass() Method
Run
public class Main {
public static void main(String[] args) {
Object obj = new Integer(5);
Class c = obj.getClass();
System.out.println("Class Name: " + c.getName());
}
}
Output
Class Name: java.lang.Integer
Explanation:
Sure, here's an example where we use the getClass() method to get the class of an object of an unknown type:
Copy code
public class Main {
public static void main(String[] args) {
Object obj = new Integer(5);
Class c = obj.getClass();
System.out.println("Class Name: " + c.getName());
}
}
In this example, we create an Object object obj and assign it a new Integer object with the value 5. Then, we call the getClass() method on the object which returns a Class object representing the runtime class of the object.
Then, we call the getName() method on the class object which returns the fully qualified name of the class.
Example 3: how to use the object getClass property:
Run
class MyClass {
private String message;
public MyClass(String message) {
this.message = message;
}
public String getMessage() {
return message;
}
}
public class Main {
public static void main(String[] args) {
MyClass obj = new MyClass("Hello World");
Class c = obj.getClass();
try {
MyClass newObj = (MyClass) c.getConstructor(String.class).newInstance("This is a new object");
System.out.println("New Object Message: " + newObj.getMessage());
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output
New Object Message: This is a new object
Explanation:
getClass() method to obtain the class of an object, and then use the class object to create a new instance of the object by using the getConstructor(String.class) and newInstance("This is a new object") methods. This can be useful in situations where you want to create multiple instances of an object at runtime, based on the type of an object.
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