04 stp android chapter4 2 en v1

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Chapter 4. Graphical UserInterfaces

Hanoi University of Science and

Technology

Nguyen Hong Quang19/8/2012

Tr!"ng #$i h%c Bch Khoa H N&iHanoi University of Science and Technology

HUST 2012


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Content! 4.2. Basic Widgets

! Images! EditText! Checkbox! RadioGroup


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4.2. Basic Widgets

Images!Android has two widgets to help embed

images in your activities:

! ImageView! ImageButton

! android:src specify what picture touse


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4.2. Basic Widgets

Images - Example


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4.2. Basic Widgets

EditText! android:autoText, to control if the field should

provide automatic spelling assistance

!android:capitalize, to control if the field shouldautomatically capitalize the first letter of enteredtext (e.g., first name, city)

! android:digits, to configure the field to accept onlycertain digits

! android:singleLine, to control if the field is forsingle-line input or multiple-line input

! (e.g., does move you to the next widget or adda newline?)


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4.2. Basic Widgets

EditText - Example

EditTextfld=(EditText)findViewById(R.id.field);

fld.setText("Licensed under the Apache

License, Version 2.0 );


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4.2. Basic Widgets

CheckBox! The classic checkbox has two states:

checked and unchecked.

! Clicking the checkbox toggles betweenthose states to indicate a choice


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4.2. Basic Widgets

CheckBox - methods! isChecked() to determine if the checkbox has been

checked

! setChecked() to force the checkbox into a checkedor unchecked state

! toggle() to toggle the checkbox as if the userchecked it

! Listener object : an instance ofCompoundButton.OnCheckedChangeListener


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4.2. Basic Widgets

CheckBox - Examples


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4.2. Basic Widgets

CheckBox - Examples

cb=(CheckBox)findViewById(R.id.check);cb.setOnCheckedChangeListener(this);


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4.2. Basic Widgets

CheckBox - Examplespublic void onCheckedChanged(CompoundButton

buttonView, boolean isChecked) {

if (isChecked) {cb.setText("This checkbox is: checked");

}

else {

cb.setText("This checkbox is: unchecked");}

}


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4.2. Basic WidgetsRadioButton

! Radio buttons are two-state, likecheckboxes, but can be grouped such that

only one radio button in the group can bechecked at any time


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4.2. Basic WidgetsRadioButton

! Like CheckBox, RadioButton inherits fromCompoundButton, which in turn inherits from

TextView. Hence, all the standard TextViewproperties for font face, style, color, etc. areavailable for controlling the look of radio buttons.

! Similarly, we can call isChecked() on aRadioButton to see if it is selected, toggle() toselect it, and so on.


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4.2. Basic WidgetsRadioGroup

! Put your RadioButton widgets inside ofa RadioGroup

! RadioGroup indicates a set of radiobuttons whose state is tied, meaning

only one button out of the group can be

selected at any time


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4.2. Basic WidgetsRadioGroup

! check() to check a specific radio button via its ID(e.g., group.check(R.id.radio1))

! clearCheck() to clear all radio buttons, so none inthe group are checked

! getCheckedRadioButtonId() to get the ID of thecurrently-checked radio button (or -1 if none arechecked)


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4.2. Basic WidgetsRadioButton - Example


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4.2. Basic WidgetsRadioButton - Exercise

! If wetoggleon the"vertical"radiobutton,

the topRadioGroupadjusts

to match


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! G!i "(RadioGroup):! setOrientation(LinearLayout.HORIZONTAL/VERTICAL);

! setGravity(Gravity.LEFT/ CENTER_HORIZONTAL/RIGHT);

T !" # i h B h Kh H N&i


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Q&A

End of Lecture

Tr!"ng #$i h%c Bch Khoa H N&iHanoi University of Science and Technology


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04 stp android chapter4 2 en v1

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