widget toolbox & views

7/27/2019 Widget Toolbox & Views

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Widget toolBox


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Android supplies a toolbox of standard Views to help you

create UIs.

Button A standard push button.

A button consists of text or an icon (or both text and an

icon) that communicates what action occurs when the user

touches it.

Depending on whether you want a button with text, anicon, or both, you can create the button in your layout in

three ways:

With text, using button class


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With an icon using ImageButton class


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Within the Activity that hosts this layout, the

following method handles the click event: /** Called when the user touches the button */

publicvoid sendMessage(View view){

// Do something in response to button click

}

The method you declare in the android:onClick attribute must have asignature exactly as shown above. Specifically, the method must:

Be public

Return void

Define a view as its only parameter (this will be the view that was

clicked)
http://developer.android.com/reference/android/app/Activity.htmlhttp://developer.android.com/reference/android/app/Activity.html


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Using an OnClickListener can declare the click event handler pragmatically rather than in an XML

layout. This might be necessary if you instantiate the Button at runtime or

you need to declare the click behavior in a Fragmentsubclass.

To declare the event handler programmatically, createan View.OnClickListener object and assign it to the button by

calling setOnClickListener(View.OnClickListener)

Eg

Button button =

(Button)findViewById(R.id.button_send);

button.setOnClickListener(newView.OnClickListener()

{

publicvoid onClick(View v){

// Do something in response to button click}

});
http://developer.android.com/reference/android/widget/Button.htmlhttp://developer.android.com/reference/android/app/Fragment.htmlhttp://developer.android.com/reference/android/view/View.OnClickListener.htmlhttp://developer.android.com/reference/android/view/View.htmlhttp://developer.android.com/reference/android/view/View.htmlhttp://developer.android.com/reference/android/view/View.OnClickListener.htmlhttp://developer.android.com/reference/android/app/Fragment.htmlhttp://developer.android.com/reference/android/widget/Button.html


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TextView A standard read-only text label that

supports multiline display, string formatting,and

automatic word wrapping.

Eg

EditText An editable text entry box that accepts

multiline entry, word-wrapping and hint text.

widget toolbox & views

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