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Access Modifiers

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Access modifiers: package-default, public
Non-access modifiers: final, abstract, or none (not obligatory)

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Constructors

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Access modifiers: private, package-default, protected, public
Non-access modifiers: none are allowed

• No return type allowed.

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Blocks

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Access modifiers: package-default
Non-access modifiers: static or none

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Members

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Access modifiers: private, package-default, protected, public
Non-access modifiers: static, final, transient, volatile, synchronized

•  If final must be initialized and cannot be volatile.

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Methods

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Access modifiers: private, package-default, protected, public
Non-access modifiers: static, final, native, strictfp

native:

• Cannot have body code, looks like abstract method e.g. public native void method();
• Must have return type void;
• Cannot be strictfp;
• Can have any other access and non-access modifier type.

Methods cannot be abstract, only abstract classes and interfaces can have abstract methods.

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Behaviours

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• Can implement one or more interfaces: has to implement all interfaces methods.
• Can extend only one class: inherits methods and members which can be overridden.
• If it extends an abstract class it must implement all abstract methods, unless this class is also abstract. Non-abstract methods and members are inherited.