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This deck focuses on Calling Instance Methods, giving you a quick way to review the definitions, rules, and examples that matter most for AP Computer Science a.
AP Computer Science a Flashcards: Calling Instance Methods
Study Calling Instance Methods in AP Computer Science a with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.
AP Computer Science a
Calling Instance Methods
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What keyword is used to refer to the current object in an instance method?
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ANSWER
this. References the current object instance within methods.
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Flashcard 1: What keyword is used to refer to the current object in an instance method?
Answer: this. References the current object instance within methods.
Flashcard 2: What is an instance method in Java?
Answer: A method that operates on an instance of a class. Operates on specific object instances and can access instance variables.
Flashcard 3: What is the access level of a method if no modifier is provided?
Answer: Package-private (default). No modifier means package-private visibility within same package.
Flashcard 4: What happens if a method is called with incorrect argument types?
Answer: A compile-time error occurs. Type mismatch prevents compilation; arguments must match parameters.
Flashcard 5: What does the return type 'void' signify in a method declaration?
Answer: The method does not return a value. Method completes without returning any data to caller.
Flashcard 6: What is the correct way to call a method 'compute' on instance 'obj'?
Answer: obj.compute();. Standard dot notation for calling methods on objects.
Flashcard 7: What is required for method overloading?
Answer: Different parameter lists. Overloading requires distinct parameter signatures for each version.
Flashcard 8: What does 'public' signify in a method declaration?
Answer: The method is accessible from any other class. Highest visibility level allowing access from any class.
Flashcard 9: What is an overloaded method?
Answer: A method with the same name but different parameters. Same name but different parameter list creates overload.
Flashcard 10: What happens if a method's return type is void and it returns a value?
Answer: A compile-time error occurs. Void methods cannot return values; causes compilation failure.
Flashcard 11: Identify the error: 'obj.method(1, 2)' when 'method' is protected.
Answer: Cannot access from outside package or subclass. Protected access requires package membership or inheritance relationship.
Flashcard 12: How do you call a method 'update' on 'obj' with 'newValue'?
Answer: obj.update(newValue);. Standard method call with single argument parameter.
Flashcard 13: Can an instance method be called without an object in Java?
Answer: No, it requires an object. Instance methods need object context to access instance data.
Flashcard 14: Identify the error: 'object.method();' when 'method' requires an argument.
Answer: Provide an argument: 'object.method(arg);'. Missing argument causes compile error; provide required parameter.
Flashcard 15: Can 'this' keyword be used in static methods?
Answer: No, 'this' is not available in static methods. 'this' refers to instance; static methods have no instance.
Flashcard 16: What does 'return' do in a method?
Answer: Exits the method and optionally returns a value. Terminates method execution and sends result to caller.
Flashcard 17: Identify the return type: 'public int getValue() { return x; }'
Answer: int. Return type appears before method name in declaration.
Flashcard 18: When is an instance method appropriate over a static method?
Answer: When the method needs to access instance fields. Instance methods can access and modify object state.
Flashcard 19: How do you call the method 'add' with integer arguments 4 and 5 on 'calc'?
Answer: calc.add(4, 5);. Pass arguments in parentheses matching parameter types.
Flashcard 20: Identify the error: 'obj.method(1, 2)' when 'method' is protected.
Answer: Cannot access from outside package or subclass. Protected access requires package membership or inheritance relationship.
Flashcard 21: What is the default return type if none is specified?
Answer: There is no default; return type must be specified. Java requires explicit return type specification for all methods.
Flashcard 22: What must match when calling an instance method with arguments?
Answer: The number, type, and order of parameters. Method signature must exactly match call arguments.
Flashcard 23: What is required to call an instance method?
Answer: An instance of the class. Instance methods must be called on specific object instances.
Flashcard 24: When is the 'this' keyword used?
Answer: To refer to the current instance of a class. Disambiguates between instance variables and parameters with same name.
Flashcard 25: What does 'protected' mean for a method's access level?
Answer: Accessible within package and subclasses. Visible to package members and subclasses only.
Flashcard 26: How do you call an instance method named 'calculate' on an object 'obj'?
Answer: obj.calculate();. Use dot notation: objectName.methodName();
Flashcard 27: Identify the error: 'obj.method(4, 5)' when 'method' takes no parameters.
Answer: Remove the arguments: 'obj.method();'. Too many arguments causes compile error; remove extras.
Flashcard 28: What is the access level of a method if no modifier is provided?
Answer: Package-private (default). No modifier means package-private visibility within same package.
Flashcard 29: What does the return type 'void' signify in a method declaration?
Answer: The method does not return a value. Method completes without returning any data to caller.
Flashcard 30: What distinguishes an instance method from a static method?
Answer: Instance methods require an object to be called; static do not. Static methods belong to class; instance methods belong to objects.
Flashcard 31: What is an overloaded method?
Answer: A method with the same name but different parameters. Same name but different parameter list creates overload.
Flashcard 32: What is method chaining?
Answer: Calling multiple methods on the same object in a single statement. Links method calls together for fluent programming style.
Flashcard 33: Can 'this' keyword be used in static methods?
Answer: No, 'this' is not available in static methods. 'this' refers to instance; static methods have no instance.
Flashcard 34: Why must a void method not have a return statement with a value?
Answer: It causes a compile-time error. Void methods cannot return values; only execution control.
Flashcard 35: Identify the error: 'object.method();' when 'method' requires an argument.
Answer: Provide an argument: 'object.method(arg);'. Missing argument causes compile error; provide required parameter.
Flashcard 36: How do you call a method 'print' with no arguments on 'printer'?
Answer: printer.print();. Empty parentheses indicate no parameters required.
Flashcard 37: What must match when calling an instance method with arguments?
Answer: The number, type, and order of parameters. Method signature must exactly match call arguments.
Flashcard 38: How do you call method 'run' with 'speed' argument on object 'vehicle'?
Answer: vehicle.run(speed);. Argument passes data to method parameter.
Flashcard 39: What is required for method overloading?
Answer: Different parameter lists. Overloading requires distinct parameter signatures for each version.
Flashcard 40: What does overloading a method allow?
Answer: Multiple methods with the same name but different parameters. Provides multiple method implementations for different parameter types.
Flashcard 41: Can an instance method be called without an object in Java?
Answer: No, it requires an object. Instance methods need object context to access instance data.
Flashcard 42: How do you call a method 'print' with no arguments on 'printer'?
Answer: printer.print();. Empty parentheses indicate no parameters required.
Flashcard 43: What is the default return type if none is specified?
Answer: There is no default; return type must be specified. Java requires explicit return type specification for all methods.
Flashcard 44: How do you call a method 'display' of class 'Screen' on an instance 'screenObj'?
Answer: screenObj.display();. Standard object.method() syntax for instance method calls.
Flashcard 45: What is the syntax to define an instance method in Java?
Answer: accessModifier returnType methodName(parameters) { body }. Standard format for declaring methods with optional parameters.
Flashcard 46: How do you call a method 'update' on 'obj' with 'newValue'?
Answer: obj.update(newValue);. Standard method call with single argument parameter.
Flashcard 47: What is the purpose of method overloading?
Answer: To define methods with the same name but different parameters. Enables multiple method versions with different parameter signatures.
Flashcard 48: What is method chaining?
Answer: Calling multiple methods on the same object in a single statement. Links method calls together for fluent programming style.
Flashcard 49: How do you call method 'display' with 'message' on object 'screen'?
Answer: screen.display(message);. Passes string argument to display method parameter.
Flashcard 50: How do you refer to the current class's method from another method?
Answer: Use 'this.methodName()'. Optional 'this.' prefix clarifies current object method call.
Flashcard 51: How do you call an instance method named 'calculate' on an object 'obj'?
Answer: obj.calculate();. Use dot notation: objectName.methodName();
Flashcard 52: What distinguishes an instance method from a static method?
Answer: Instance methods require an object to be called; static do not. Static methods belong to class; instance methods belong to objects.
Flashcard 53: When is an instance method appropriate over a static method?
Answer: When the method needs to access instance fields. Instance methods can access and modify object state.
Flashcard 54: What is the effect of calling a method with no return statement?
Answer: If non-void, causes a compile-time error. Non-void methods must return value; missing return fails compilation.
Flashcard 55: What is the syntax to define an instance method in Java?
Answer: accessModifier returnType methodName(parameters) { body }. Standard format for declaring methods with optional parameters.
Flashcard 56: What happens if a method is called with incorrect argument types?
Answer: A compile-time error occurs. Type mismatch prevents compilation; arguments must match parameters.
Flashcard 57: What is the purpose of method overloading?
Answer: To define methods with the same name but different parameters. Enables multiple method versions with different parameter signatures.
Flashcard 58: What keyword is used to refer to the current object in an instance method?
Answer: this. References the current object instance within methods.
Flashcard 59: Identify the error in 'obj.calculate()' when 'calculate' is private.
Answer: Cannot access private method from outside class. Private methods only accessible within same class.
Flashcard 60: What does overloading a method allow?
Answer: Multiple methods with the same name but different parameters. Provides multiple method implementations for different parameter types.
Flashcard 61: What does 'public' signify in a method declaration?
Answer: The method is accessible from any other class. Highest visibility level allowing access from any class.
Flashcard 62: Identify the error: 'obj.method(4, 5)' when 'method' takes no parameters.
Answer: Remove the arguments: 'obj.method();'. Too many arguments causes compile error; remove extras.
Flashcard 63: How do you call method 'display' with 'message' on object 'screen'?
Answer: screen.display(message);. Passes string argument to display method parameter.
Flashcard 64: Identify the return type: 'public int getValue() { return x; }'
Answer: int. Return type appears before method name in declaration.
Flashcard 65: When is the 'this' keyword used?
Answer: To refer to the current instance of a class. Disambiguates between instance variables and parameters with same name.
Flashcard 66: How do you call method 'run' with 'speed' argument on object 'vehicle'?
Answer: vehicle.run(speed);. Argument passes data to method parameter.
Flashcard 67: How do you refer to the current class's method from another method?
Answer: Use 'this.methodName()'. Optional 'this.' prefix clarifies current object method call.
Flashcard 68: What is required to call an instance method?
Answer: An instance of the class. Instance methods must be called on specific object instances.
Flashcard 69: How do you call the method 'add' with integer arguments 4 and 5 on 'calc'?
Answer: calc.add(4, 5);. Pass arguments in parentheses matching parameter types.
Flashcard 70: Why must a void method not have a return statement with a value?
Answer: It causes a compile-time error. Void methods cannot return values; only execution control.
Flashcard 71: How do you call a method 'display' of class 'Screen' on an instance 'screenObj'?
Answer: screenObj.display();. Standard object.method() syntax for instance method calls.
Flashcard 72: What is the effect of calling a method with no return statement?
Answer: If non-void, causes a compile-time error. Non-void methods must return value; missing return fails compilation.
Flashcard 73: What happens if a method's return type is void and it returns a value?
Answer: A compile-time error occurs. Void methods cannot return values; causes compilation failure.
Flashcard 74: Identify the error in 'obj.calculate()' when 'calculate' is private.
Answer: Cannot access private method from outside class. Private methods only accessible within same class.
Flashcard 75: What is the role of parameters in an instance method?
Answer: They allow input to be passed to the method. Parameters accept data from caller for method processing.
Flashcard 76: What is the role of parameters in an instance method?
Answer: They allow input to be passed to the method. Parameters accept data from caller for method processing.
Flashcard 77: What does 'protected' mean for a method's access level?
Answer: Accessible within package and subclasses. Visible to package members and subclasses only.
Flashcard 78: What does 'return' do in a method?
Answer: Exits the method and optionally returns a value. Terminates method execution and sends result to caller.
Flashcard 79: What is the correct way to call a method 'compute' on instance 'obj'?
Answer: obj.compute();. Standard dot notation for calling methods on objects.
Flashcard 80: What is an instance method in Java?
Answer: A method that operates on an instance of a class. Operates on specific object instances and can access instance variables.