Android learning basics-engineering file Composition

1 SRC Source File Folder COM. example. appname package name mainactivity activity class Gen save automatically generated R Resource class folder com. example. appname package name R. android 3.0-> android. jar Android sdk jar file assets save the res resource folder of the original resource file drawable Save image and other resource folders drawable.icon.png .. save icons and other external resource files layout interface layout folder Layout-> main. XML interface layout file values simple Value configuration folder values-> strings. XML string configuration file androidmainfest. XML Android configuration list file 2 mainactivity. java, inheriting activity class, medium Call the setcontentview method to display the View Interface public class main extends activity {protected void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. activity_main);} r. layout. activity_main is R. A property in the Java Resource class 3 R. java program code public final class r {public static final class ATTR {} public static final class dimen {public static final int activity_horizontal_margin = 0x7f040000; Publ IC static final int ready = 0x7f040001;} public static final class drawable {public static final int ic_launcher = 0x7f020000;} public static final class ID {public static final int action_settings = 0x7f080000 ;} public static final class layout {public static final int activity_main = 0x7f030000;} public static final Class Menu {public static final int main = 0x7f070000;} public Static final class string {public static final int action_settings = 0x7f050001; public static final int app_name = 0x7f050000; public static final int hello_world = 0x7f050002 ;} public static final class style {public static final int appbasetheme = 0x7f060000;/** application theme. all mizmizations that are not specific to a special API-level can go here. */public static final int apptheme = 0x7 F060001 ;}} the file is automatically generated by the system. attributes are declared in ATTR. Some image resources are declared in drawable. layout declares the layout file. setcontentview (R. layout. activity_main) is used to access the activity_main.xml layout file in the layout folder of the project by accessing the activity_main attribute of the internal class layout of the Resource class R. The view component string is displayed on the interface. XML to declare the string constants used in the system. Code <relativelayoutxmlns: Android = "http://schemas.android.com/apk/res/android" xmlns: Tools = "http://schemas.android.com/tools" Android: layout_width = "match_parent" Android: layout_height = "match_parent" Android: paddingbottom = "@ dimen/activity_vertical_margin Android: paddingleft =" @ dimen/plugin "Android: paddingright =" @ dimen/plugin "Android: paddingtop = "@ dimen/activity_vertical_margin" tools: context = ". main "> <textview Android: layout_width =" wrap_content "Android: layout_height =" wrap_content "Android: TEXT = "@ string/hello_world"/> </relativelayout> the first behavior is relative to relativelayout, the vertical attribute indicates that the component is vertically placed fill_parent, indicating that the layout width is filled with the parent component wrap_content, indicating that the component width is filled with the parent-child 3 androidmanifest. XML, which is a global configuration file of the android project. All the components used are declared in this file.