6 Packages O com. exampl p□util Rjava co ActivityA Sb Activity B So ActivityC ta BuildConfig R java: hook the resources and java by b a drawable-hdpi b a drawable-ldpi □ drawable-mdpi providing each resource item an ID o drawable-xhdpi b a layout Ovals Reference a resource in java codes liBraries [<package name>.R <resource type>. <resource name> o <package name>: name of the package in which the resource is located (not required when referencing resources from your own package) <resource type: resource type o <resource name>: the resource filename without the extension or the android name attribute value in the xml element findviewbyId(r. id ***) identify a view on Xml by its id setContentView(R layout. ***): apply the layout for the content view 10• Reference a resource in Java codes o <package_name>: name of the package in which the resource is located (not required when referencing resources from your own package). o <resource_type>: resource type. o <resource_name>: the resource filename without the extension or the android:name attribute value in the XML element. R.java • R.java: hook the resources and java by providing each resource item an ID 10 [<package_name>.]R.<resource_type>.<resource_name> • findViewById(R.id.***): identify a view on XML by its id • setContentView(R.layout.***): apply the layout for the content view