Transcript se1021-5-3-GuiLayoutAndActionListener

SE-1021
Software Engineering II
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Week 5, Class 3
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Completing the Calculator GUI layout
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Dr. Josiah Yoder
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How can we create this
calculator layout?
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+
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-
*
/
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Modify the code below
to put the operators
above the buttons…
/// in the constructor…
setLayout(new BorderLayout());
JPanel panel = createButtonPanel();
add(panel,BorderLayout.CENTER);
public JPanel createOperationPanel() {
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JPanel panel = new JPanel();
panel.add(new JButton("+"));
panel.add(new JButton("-"));
panel.add(new JButton("*"));
panel.add(new JButton("/"));
return panel;
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Dr. Josiah Yoder
}
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Get to know your classmates
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Turn to a neighbor, and find out who traveled
farther over Christmas break
When you have determined who traveled
farther, that person should raise his hand
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Dr. Josiah Yoder
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What do we need to do to get
our GUI to respond?
In your groups of 2…
 Write a list of as many things that you can
think of as possible to complete the GUI
application.
 Favor quantity over quality
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Dr. Josiah Yoder
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What is an inner class?
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An inner class is
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Declared inside of another class
Usually declared private (needed by only one
class)
Has access to all variables of the top-level class
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Even instance variables!
And so … _____________________________
Even private variables!
And so … ______________________________
Dean & Dean, 2nd Ed. Pp 775-776 (Sec. 17.10)
http://docs.oracle.com/javase/tutorial/java/javaOO/n
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Dr. Josiah Yoder
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Anonymous Inner Class
This is a class that is DECLARED at the same
place it is INSTANTIATED in the program
Syntax:
new InterfaceName () {
ClassBody
}
Use: Use it where you would use the
constructor of the class
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Dr. Josiah Yoder
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Lambda Expression
A lambda expression is an anonymous inner
class with shorter syntax, for interfaces with just
one method.
Example:
e -> myMethod(e)
Use: Use it where you would use a constructor
or an anonymous inner class.
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Dr. Josiah Yoder
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From the Horse’s Mouth*
“Lambda expressions let you express
instances of single-method classes more
compactly.”
http://docs.oracle.com/javase/tutorial/java/java
OO/lambdaexpressions.html (emphasis added)
* “straight from the Horse’s mouth” is an idiom
saying to get something from an authoritative
source. It refers to looking into a horse’s mouth
to determine its age.
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Dr. Josiah Yoder
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Answer this question
Example lambda expression:
e->System.out.println(e.getActionCommand())
Can a lambda expression use instance
variables? How about instance methods?
Think alone 1 minutes, discuss in pairs 1
minute
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Dr. Josiah Yoder
Slide style: Dr. Hornick
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