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Today, we are going to explore one of the most important concepts in Java, defining classes

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and creating objects. By the end of this lesson, students will be able to explain what a class

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and an object are in Java. Write a simple Java class with fields and methods.

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Create and access objects using the new operator and dot notation.

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Identify common mistakes when working with objects, such as null references and naming errors.

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Understanding classes. In Java, a class is like a blueprint for creating objects.

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It tells us what information the object will store and what actions it can perform.

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For example, if we create a class called person, we could include two fields, name and age.

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These fields hold the state of each person object. We can also add a method like say hello,

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which prints a greeting. So, a class combines both attributes and behaviors in one structure.

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Creating objects. Once the class is ready, we can bring it to life by creating objects.

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We use the new operator to do this. Person P equals new person. After creating the object,

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we can assign values using dot notation, like p.name equals Alice and p.age equals 30.

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Calling p.say hello makes the object run its method. This is how we move from just a class

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blueprint to an active object that stores real data and performs actions.

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Multiple objects and memory. Every time we type new person, Java creates a separate

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object in heap memory. So, if we write person p.2 equals new person and set its name to Bob,

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it works independently from Alice's object. Even though both objects come from the same class,

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their values are stored separately. This helps us clearly distinguish attributes of different objects.

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Practice and pitfalls. Soon, you'll get hands-on practice by creating a book class with fields

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like title and author, plus a method print info. Then you'll build multiple book objects and

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display their information. But remember two common pitfalls. First, avoid null references.

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Don't access fields before creating the object. And second, watch out for typos in variable

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and method names, because even tiny mistakes can cause errors. Understanding these points will

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make you confident in working with Java classes and objects. By mastering how to define classes

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and create objects, you'll take your first major step into object-oriented programming, the heart

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of Java.