Creating and Enriching Graphical User Interfaces - Beginning Java 7 - page 605

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}
fixGUI(Frame) isinvokedwithareferencetothe TempVerter framewindow
( TempVerter.this provides that reference). It first invokes
f.getComponents()[0] toobtainthepanelthatwasaddedtotheframewindow.
( Listing 7-2 identifies this panel as pnlLayout .)
pnl / pnlLayout contains three Panel instances (recall pnlTemp ). The second
line fetches the first of these instances and assigns its reference to pnlRow . The third
lineextractstheDegreeslabelcomponent,whichisthefirstcomponent(atposition0)
within this panel.
Thefourthlinefetchesthesecond Panel instancethatcontainstheResultlabeland
its associated textfield. The fifth line extracts this label.
The sixth line invokes getPreferredSize() on the Result label, and then in-
vokes Component 's void setPreferredSize(Dimension preferredS-
ize) method with this preferred size to shrink the width of the Degrees label so that
both textfields are left-aligned.
The seventh line fetches the third Panel instance, which contains the two buttons,
theeighthandninthlinesextractthesebuttons,andthetenthlinesetsthepreferredsize
of the Convert to Celsius button to that of the wider Convert to Fahrenheit button.
Introducing fixGUI(Frame) into TempVerter is only part of the solution. We
mustalsocallthismethod,andtheappropriateplacetodosoisbetweentheframewin-
dow's pack() and setVisible() method calls.
fixGUI() mustbecalledafter pack() becausethepreferredsizesarenotknown
until after pack() has been called. This method must be called before setVis-
ible() becauseitchangespreferredsizes. setVisible() canaccommodatethese
changeswhentheyaremadebeforethismethodiscalled.However,whentheyaremade
after calling setVisible() , pack() will have to be called a second time.
Note Although fixGUI() isconvenientfortrivialapplications,youwon'tneedto
useitafterlearningmoreaboutlayoutmanagement(whichunfortunatelyisbeyondthe
scope of this chapter). fixGUI() can be tedious to code, and you need to revise it
whenever you change the GUI.Graphics, Colors, and Fonts
The Component class declares a void paint(Graphics g) method to paint
a component. Painting occurs when a component is first shown or when it has been
damaged(bybeingpartlyorcompletelyobscuredbyanothercomponent)andisbeing
reshown.