©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 1 Sample Animated Slides for Wu, Intro to OOP with Java 4 th Ed Start the slide presentation and press the down arrow or the Enter key to proceed through animation. Press the up key to back up.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 2 Declaration vs. Creation Customer customer; customer = new Customer( ); Customer customer; customer = new Customer( ); 1. The identifier customer is declared and space is allocated in memory. 2. A Customer object is created and the identifier customer is set to refer to it. 1 2 customer 1 : Customer 2

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 3 Name vs. Objects Customer customer; customer = new Customer( ); Customer customer; customer customer = new Customer( ); : Customer Created with the first new. Created with the second new. Reference to the first Customer object is lost.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 4 Sending a Message myWindow. setVisible ( true ) ; More Examples account.deposit( ); student.setName(“john”); car1.startEngine( ); Object Name Name of the object to which we are sending a message. Object Name Name of the object to which we are sending a message. Method Name The name of the message we are sending. Method Name The name of the message we are sending. Argument The argument we are passing with the message. Argument The argument we are passing with the message.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 5 JFrame myWindow; myWindow = new JFrame( ); myWindow.setSize(300, 200); myWindow.setTitle (“My First Java Program”); myWindow.setVisible(true); Execution Flow myWindow.setSize(300, 200); Jframe myWindow; myWindow myWindow.setVisible(true); State-of-Memory Diagram : JFrame width height title visible 200 My First Java … 300 true myWindow = new JFrame( ); myWindow.setTitle (“My First Java Program”); The diagram shows only four of the many data members of a JFrame object. Program Code

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 6 String is an Object 1. The identifier name is declared and space is allocated in memory. 2. A String object is created and the identifier name is set to refer to it. 1 2 name 1 String name; name = new String(“Jon Java”); String name; name = new String(“Jon Java”); 2 : String Jon Java

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 7 Definition: length Assume str is a String object and properly initialized to a string. str.length( ) will return the number of characters in str. If str is “programming”, then str.length( ) will return 11 because there are 11 characters in it. The original string str remains unchanged.

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 8 Examples: length String str1, str2, str3, str4; str1 = “Hello” ; str2 = “Java” ; str3 = “” ; //empty string str4 = “ “ ; //one space str1.length( ) str2.length( ) str3.length( ) str4.length( )

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 9 Primitive Data Declaration and Assignments Code State of Memory int firstNumber, secondNumber; firstNumber = 234; secondNumber = 87; A A int firstNumber, secondNumber; B B firstNumber = 234; secondNumber = 87; int firstNumber, secondNumber; firstNumber = 234; secondNumber = 87; firstNumber secondNumber A. A. Variables are allocated in memory. B. B. Values are assigned to variables

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 10 Assigning Numerical Data Code State of Memory int number; number = 237; number = 35; number A. A. The variable is allocated in memory. B. 237 number B. The value 237 is assigned to number. 237 int number; number = 237; number = 35; A A int number; B B number = 237; C C number = 35; C C. The value 35 overwrites the previous value

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 11 Assigning Objects Code State of Memory Customer customer; customer = new Customer( ); customer A. A. The variable is allocated in memory. Customer customer; customer = new Customer( ); A A Customer customer; B B customer = new Customer( ); C C B. customer B. The reference to the new object is assigned to customer. Customer C. customer. C. The reference to another object overwrites the reference in customer. Customer

©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 th Ed Sample Slides - 12 Having Two References to a Single Object Code State of Memory Customer clemens, twain; clemens = new Customer( ); twain = clemens; Customer clemens, twain, clemens = new Customer( ); twain = clemens; A A Customer clemens, twain; B B clemens = new Customer( ); C C twain = clemens; A. A. Variables are allocated in memory. clemens twain B. clemens B. The reference to the new object is assigned to clemens. Customer C. clemens customer. C. The reference in clemens is assigned to customer.