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Programming with Android: Calculator Example Luca Bedogni Marco Di Felice Dipartimento di Informatica: Scienza e Ingegneria Università di Bologna.

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Presentation on theme: "Programming with Android: Calculator Example Luca Bedogni Marco Di Felice Dipartimento di Informatica: Scienza e Ingegneria Università di Bologna."— Presentation transcript:

1 Programming with Android: Calculator Example Luca Bedogni Marco Di Felice Dipartimento di Informatica: Scienza e Ingegneria Università di Bologna

2 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example 2 Calculator: Outline Today: How to build a Calculator? Define the layout of the application Create an application that uses this layout Add some sort of intelligence to the application Test it

3 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout Define the buttons, labels, cells and so on Place them on the screen Pay attention: Android powered phones are very different in terms of resolutions Try not to stick with absolute values/positioning (we will see this later)

4 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition

5 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition First Operand

6 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition First Operand Operator

7 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition First Operand Operator Second Operand

8 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition First Operand Operator Second Operand Result

9 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition First Operand Operator Second Operand Result Operators

10 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout definition First Operand Operator Second Operand Result Operators

11 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: logic definition Whenever a user selects a operand cell, a keyboard will pop up Pressing an operator button will switch the focus from one operand to another (except for =) We want to deal with float numbers

12 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: events We want to be warned when a user touches something on the screen Every time this happens, we will react with a set of actions The MVC pattern is relaxed that way (pros and cons) We do not want the result to be focusable

13 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout building We will use a set of layouts Layouts are grouped together following a hierarchy Why not absolute positioning?

14 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout building We will use a set of layouts Layouts are grouped together following a hierarchy Why not absolute positioning? Android has a wide range of devices Wide range of resolution Wide range of capabilities

15 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: layout building We will use a set of layouts Layouts are grouped together following a hierarchy Why not absolute positioning? Android has a wide range of devices Wide range of resolution Wide range of capabilities Need to build dynamic applications that performs different depending on the device they're running in.

16 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: hierarchy viewer

17 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: Recap Define a Layout – Pay Attention to devices heterogeneity Features – Keyboard should pop up when needed Should not pop up on the result – Switch from one cell to another when pressing operand React to Events

18 Luca Bedogni, Marco Di Felice - Programming with Android – Calculator Example Calculator: start Let's start developing the calculator


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