android - Prevent logout of the application on backpressed -

i got problem regarding application,after login leads home page.in homepage on backpressed application gets logout.next time when going open app starts again login page.

i have passed value , set notification also,i don't know how prevent me @thanks

• save login details in sharedpreferences.

to save login details sharedpreference

sharedpreferences sp = context.getsharedpreferences("loginsaved", context.mode_private); sharedpreferences.editor editor = sp.edit(); editor.putstring("username", "some user value"); editor.putstring("password", "some password value"); editor.commit(); 

• check if there value in sharedpreference on opening login page.
• if login details saved in sharedpreference go home page.else show login page.

to check logged in or not

sharedpreferences sp = context.getsharedpreferences("loginsaved", context.mode_private); string username = sp.getstring("username", null); string password = sp.getstring("password", null); if(username != null && password != null){     // login automatically username , password     } else{     // show login page } 

• clear logindetails sharedpreference when user correctly logout.