CSE110 Lecture 16

Principles of Programming with Java
Classes and Objects
(202005)

Transcript

1. CSE110
   Principles of Programming
   with Java
   Lecture 16:
   Classes and Objects
   Javier Gonzalez-Sanchez
   javiergs@asu.edu
   javiergs.engineering.asu.edu | javiergs.com
   Office Hours: By appointment
   

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2. static keyword
   

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3. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 3
   static
   class
   static int variable1;
   public static void sayHelloAll(){
   }
   int variable2;
   public void sayHello (){
   }
   

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4. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 4
   static
   • Non-static methods can use static and non-static
   variables
   • static methods can only use static variables.
   • static variable = class variable
   • Non-static variable =
   instance/object variables/attributes.
   

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5. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 5
   static
   class
   static int variable1;
   public static void sayHelloAll(){
   variable1 =0;
   variable2 =0;
   }
   int variable2;
   public void sayHello (){
   variable1 =0;
   variable2 =0;
   }
   

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6. Communication
   Call and Create Methods
   

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7. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 7
   Object-Oriented Paradigm
   public class Student {
   String name;
   int finalGrade;
   public void sayHello(){
   // print name
   }
   public void drawSomething(){
   // draw
   }
   }
   public class MyProgram {
   public static void main(String [] arg) {
   Student john = new Student();
   john.name = "John Doe";
   john.sayHello();
   jane.name = "Jane Doe";
   jane.sayHello();
   }
   }
   john jane
   

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8. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 8
   Call Methods
   • john.sayHello();
   • john.sayHello("in French");
   • int x = john.giveMeANumber();
   • int result = john.addThisNumbers(2,2);
   

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9. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 9
   Create Methods
   • public void sayHello() { }
   • public void sayHello(String language) {}
   • public int giveMeANumber(){}
   • public int addThisNumbers(int x, int y) {}
   

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10. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 10
    Methods
    • public or private
    • static (optional)
    • type (void, int, double, String, etc.)
    • name
    • (parameters)
    • { body }
    

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11. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 11
    Example
    

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12. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 12
    Example
    

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13. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 13
    Example
    

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14. Javier Gonzalez-Sanchez | CSE110 | Summer 2020 | 14
    Reference
    Pages 201 - 207
    

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15. CSE110 - Principles of Programming
    Javier Gonzalez-Sanchez
    javiergs@asu.edu
    Summer 2020
    Disclaimer. These slides can only be used as study material for the class CSE110 at ASU. They cannot be distributed or used for another purpose.
    

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