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Start your free trialRashad Hill
1,708 PointsQuestion regarding syntax of xml code
The challenge asked me to use "@id" as opposed to "@+id" and I see some parts of the code that uses the latter as opposed to the former, what's the difference?
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<EditText
android:id="@+id/captionField"
android:layout_alignParentTop="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:hint="Enter a caption" />
<ImageView
android:id="@+id/imageView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:src="@drawable/grumpy_cat"
android:layout_below="@id/captionField"/>
</RelativeLayout>
1 Answer
alladin
2,873 Points@+id: is used when we have to create an id and add it to the R file for the first time for a new element. @id if an id has already been created. As shown in the code snippet above @+id : <EditText android:id="@+id/captionField" when creating id for this EditText to be referred from here onwards.
Inside ImageView android:layout_below="@id/captionField"/> this line now just referring to the id captionField and not creating it again to be added to R file
Ryan Sheets
5,337 PointsRyan Sheets
5,337 Points@+id is used to define a new identifier and must be used at the first occurrence of each identifier in the layout. @id simply references an existing identifier and should be used for all subsequent instances of that identifier.