- #[[CT2106 - Object-Oriented Programming]]
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- **Next Topic:** [[Introduction to Java]]
- **Relevant Slides:** ![Lecture00.pdf](../assets/Lecture00_1662850272554_0.pdf)
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- ## Definitions
	- What is a **class**? #card
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		- A **class** is a type of *blueprint* or *template* from which you make objects.
	- What is an **object**? #card
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		- A (Java) **object** is a self-contained component which consists of *methods* and *properties*.
		- It is a piece of code that has a **state** and has **behaviour**.
		- Often, they represent a "real-life" object.
		- An object is created by *instantiating* a **class**.
	- What is **bytecode**? #card
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		- Unlike other high-level programming languages, Java code is **not** compiled into machine-specific code that can be executed by a microprocessor.
		- Instead, Java programs are compiled into **bytecode**. The bytecode is input into a **Java Virtual Machine (JVM)**, which interprets & executes the code. The JVM is usually a program itself.
		- Bytecode is **platform independent**.
		- The JVM is specific for each platform, but the bytecode for the program remains the same across different platforms.
		- The main trade-off is the effect it has on the execution speed.
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