Android mini project-File Browser

The layout file will not be pasted. It is very simple to use two XML files. I try to clarify the comments of the Code.

Package COM. example. demofilebrower; import Java. io. file; import Java. io. ioexception; import Java. util. arraylist; import Java. util. hashmap; import Java. util. list; import Java. util. map; import android. app. activity; import android. OS. bundle; import android. view. menu; import android. view. view; import android. view. view. onclicklistener; import android. widget. adapterview; import android. widget. adapterview. onitemclickl Istener; import android. widget. button; import android. widget. listview; import android. widget. simpleadapter; import android. widget. textview; import android. widget. toast; public class mainactivity extends activity {private textview showdir; private button; private listview; file currentparent; file [] currentfiles; @ overridepublic void oncreate (bundle savedinstancestate) {super. oncreate (savedins Tancestate); setcontentview (R. layout. activity_main); this. showdir = (textview) findviewbyid (R. id. textview1); this. button = (button) findviewbyid (R. id. button1); this. listview = (listview) findviewbyid (R. id. listview1); file root = new file ("/mnt/sdcard/"); If (root. exists () {currentparent = root; // The current parent path currentfiles = root. listfiles (); // all files in the current path inflatelistview (currentfiles);} listview. setonitemclicklis Tener (New onitemclicklistener () {public void onitemclick (adapterview <?> Parent, view, int position, long ID) {If (currentfiles [position]. isfile () {return;} file [] TMP = currentfiles [position]. listfiles (); If (TMP = NULL | TMP. length = 0) {toast. maketext (getapplicationcontext (), "No files in the current path or cannot be accessed", toast. length_long ). show () ;}else {currentparent = currentfiles [position]; currentfiles = TMP; inflatelistview (currentfiles) ;}}); // return the button in the upper-level directory. setonclicklistener (New on Clicklistener () {public void onclick (view v) {try {If (! Currentparent. getCanonicalPath (). equals ("/mnt/sdcard") {currentparent = currentparent. getparentfile (); currentfiles = currentparent. listfiles (); inflatelistview (currentfiles) ;}} catch (exception e) {}});} private void inflatelistview (file [] files) {// todo auto-generated method stublist <Map <string, Object> listitems = new arraylist <Map <string, Object> (); For (INT I = 0; I <files. length; I ++) {Map <String, Object> listitem = new hashmap <string, Object> (); If (files [I]. isdirectory () {// if it is a path, set the path icon listitem. put ("icon", R. drawable. ic_launcher);} else {// if it is a file, set the file icon. Listitem. put ("icon", R. drawable. ic_action_search);} listitem. put ("FILENAME", files [I]. getname (); listitems. add (listitem);} simpleadapter = new simpleadapter (this, listitems, R. layout. line, new string [] {"icon", "FILENAME"}, new int [] {R. id. imageview1, R. id. textview1}); listview. setadapter (simpleadapter); try {showdir. settext ("current path:" + currentparent. getCanonicalPath ();} catch (ioexception e) {e. printstacktrace () ;}@ overridepublic Boolean oncreateoptionsmenu (menu) {getmenuinflater (). inflate (R. menu. activity_main, menu); Return true ;}}