Constructors are the member functions which are called automatically whenever an object is created. It is a mandatory functions to be called for an object to be created as this helps in initializing the object to a legal initial value for the class. Recommended textbooks for you  Programming Logic & Design Comprehensive EBK JAVA PROGRAMMING Publisher:CENGAGE LEARNING - CONSIGNMENT Microsoft Visual C# Publisher:Cengage Learning, EBK JAVA PROGRAMMING Publisher:CENGAGE LEARNING - CONSIGNMENT Programming Logic & Design Comprehensive ISBN:9781337669405 Author:FARRELL Publisher:Cengage EBK JAVA PROGRAMMING ISBN:9781337671385 Author:FARRELL Publisher:CENGAGE LEARNING - CONSIGNMENT Microsoft Visual C# ISBN:9781337102100 Author:Joyce, Farrell. Publisher:Cengage Learning, EBK JAVA PROGRAMMING ISBN:9781305480537 Author:FARRELL Publisher:CENGAGE LEARNING - CONSIGNMENT - method that is automatically called when an object is created○Perform■Initialization■Setup operations (storing initial values in instance fields)○Help construct an object○Same name as class○Header doesn’t specify return type■Not executed by explicit method calls■Cannot return a value●Several ways to show class’s constructor in UML diagram●Uninitialized reference variable- reference variables can also be declared without beinginitialized○Eg. Rectangle box;○After declaring, statement can be used to assign it the address of an object■Eg. box = new Rectangle(7.0, 14.0);●Creates Rectangle object●Passes values to constructor●Assigns object’s address to box variable○Be careful when using!■Local variables must be initialized or assigned a value before that can beused■Local reference variable must reference an object before it can be used●If you don’t write a constructor in a class, Java automatically provides one when theclass is compiled○Default constructor○Doesn’t accept arguments○Sets all object’s numerical fields to 0 and boolean to false○If object has field, set to null, so they don’t reference anything●No-arg constructor- constructor that does not accept arguments○Eg. default constructor●Create primitive variables with simple declaration statements●Create objects with new operator●Can create String objects in same way as primitive variables6.5 PASSING OBJECTS AS ARGUMENTS●When an object is passed as an argument to a method, the object’s address is passed |
The method is automatically called when an object is created.
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