Combination of ListView and SQLite in Android studio

Da.java

 Public classDbextendsSqliteopenhelper { PublicDb (Context context) {Super(Context, "DB",NULL, 1); } @Override Public voidonCreate (Sqlitedatabase db) {Db.execsql ("CREATE TABLE user2 (" + "_id INT default 0," + "name TEXT default \" \ "," + "s Ex TEXT DEFAULT \ "\") "); } @Override Public voidOnupgrade (Sqlitedatabase db,intOldversion,intnewversion) {    }}

Mainactivity.java

 Public classMainactivityextendsappcompatactivity {PrivateSimplecursoradapter Madapter; PrivateListView ListView; PrivateButton Btn_add; PrivateButton Btn_delete; PrivateButton Btn_back; PrivateEditText et_id; PrivateEditText Et_name; PrivateEditText Et_sex; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); Btn_add=(Button) Findviewbyid (R.id.btn_add); Btn_delete=(Button) Findviewbyid (r.id.btn_delete); ListView=(ListView) Findviewbyid (r.id.list); Btn_add.setonclicklistener (NewView.onclicklistener () {@Override Public voidOnClick (View v) {addData ();            Refleshlistview ();        }        }); Btn_delete.setonclicklistener (NewView.onclicklistener () {@Override Public voidOnClick (View v) {deleteData ();            Refleshlistview ();        }        }); Listview.setonitemclicklistener (NewAdapterview.onitemclicklistener () {@Override Public voidOnitemclick (adapterview<?> Parent, view view,intPositionLongID) {//Toast.maketext (Mainactivity.this, "" +position,toast.length_short). Show ();                intpositions = position + 1; DB DB=NewDb (mainactivity. This); Sqlitedatabase Dbwrite=db.getwritabledatabase (); Dbwrite.delete ("User2", "_id=?",Newstring[]{"" +positions});                Dbwrite.close ();            Refleshlistview ();    }        }); }     Public voidAddData () {Btn_back=(Button) Findviewbyid (r.id.btn_back); et_id=(EditText) Findviewbyid (r.id.et_id); Et_name=(EditText) Findviewbyid (r.id.et_name); Et_sex=(EditText) Findviewbyid (r.id.et_sex); Btn_add=(Button) Findviewbyid (R.id.btn_add); Btn_delete=(Button) Findviewbyid (r.id.btn_delete); ListView=(ListView) Findviewbyid (r.id.list);        Btn_add.setvisibility (View.gone);        Btn_delete.setvisibility (View.gone);        Listview.setvisibility (View.gone);        Btn_back.setvisibility (view.visible);        Et_id.setvisibility (view.visible);        Et_name.setvisibility (view.visible);        Et_sex.setvisibility (view.visible); Btn_back.setonclicklistener (NewView.onclicklistener () {@Override Public voidOnClick (View v) {btn_add.setvisibility (view.visible);                Btn_delete.setvisibility (view.visible);                Listview.setvisibility (view.visible);                Btn_back.setvisibility (View.gone);                Et_id.setvisibility (View.gone);                Et_name.setvisibility (View.gone);                Et_sex.setvisibility (View.gone); String ID=Et_id.gettext (). toString (), name=Et_name.gettext (). toString (), Sex=Et_sex.gettext (). toString (); DB DB=NewDb (mainactivity. This); Sqlitedatabase Dbwrite=db.getwritabledatabase (); Contentvalues CV=Newcontentvalues (); Cv.put ("_ID", id); Cv.put ("Name", name); Cv.put ("Sex", Sex); Dbwrite.insert ("User2",NULL, CV);                Dbwrite.close ();            Refleshlistview (); }        });//String id = et_id.gettext (). toString (),//name =et_name.gettext (). toString (),//sex = Et_sex.gettext (). toString ();//////db db = new db (mainactivity.this);//sqlitedatabase dbwrite = Db.getwritabledatabase ();////contentvalues CV = new Contentvalues ();//cv.put ("_id", id);//cv.put ("name", name);//cv.put ("Sex", sex);//Dbwrite.insert ("User2", NULL, CV);////dbwrite.close ();    }     Public voidDeleteData () {db db=NewDb (mainactivity. This); Sqlitedatabase Dbwrite=db.getwritabledatabase (); Dbwrite.delete ("User2",NULL,Newstring[]{});    Dbwrite.close (); }     Public voidRefleshlistview () {db db=NewDb (mainactivity. This); Sqlitedatabase DBRead=db.getreadabledatabase (); Cursor C= Dbread.query ("User2",NULL,NULL,NULL,NULL,NULL,NULL); Madapter=NewSimplecursoradapter (mainactivity. This, R.layout.user_info, C,Newstring[]{"_id", "name", "Sex"},New int[]{r.id._id,r.id._name,r.id._sex}];        Listview.setadapter (Madapter);    Dbread.close (); }}

User_info.xml

<linearlayout xmlns:android= "Http://schemas.android.com/apk/res/android"Android:layout_width= "Match_parent"Android:layout_height= "Match_parent"android:orientation= "Horizontal" > <TextView Android:id= "@+id/_id"android:textsize= "20SP"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"/> <TextView Android:id= "@+id/_name"android:textsize= "20SP"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"/> <TextView Android:id= "@+id/_sex"android:textsize= "20SP"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"/></linearlayout>

Activity_main.xml

<linearlayout xmlns: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:orientation= "Vertical"Tools:context=". Mainactivity "> <Button Android:id= "@+id/btn_add"Android:text= "Add"android:textsize= "20SP"Android:layout_width= "Match_parent"Android:layout_height= "Wrap_content"/> <Button Android:id= "@+id/btn_delete"Android:text= "Delete"android:textsize= "20SP"Android:layout_width= "Match_parent"Android:layout_height= "Wrap_content"/> <ListView Android:id= "@+id/list"Android:layout_width= "Match_parent"Android:layout_height= "Wrap_content"/> <Button Android:id= "@+id/btn_back"Android:text= "OK"android:textsize= "20SP"Android:layout_width= "Match_parent"Android:layout_height= "Wrap_content"/> <EditText Android:id= "@+id/et_id"android:visibility= "Gone"Android:layout_width= "Match_parent"Android:layout_height= "40DP"/> <EditText Android:id= "@+id/et_name"android:visibility= "Gone"Android:layout_width= "Match_parent"Android:layout_height= "40DP"/> <EditText Android:id= "@+id/et_sex"android:visibility= "Gone"Android:layout_width= "Match_parent"Android:layout_height= "40DP"/></linearlayout>

Combination of ListView and SQLite in Android studio