java - How do I add to ListView and not replace it? -

i'm new android , i'm trying add things listview activity. able add things list, each time add list replaces entered.

i have tried using notifydatasetchanged() invalidateviews() neither seem work?

here related files:

activity_main.xml

<?xml version="1.0" encoding="utf-8"?> <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:paddingleft="@dimen/activity_horizontal_margin"     android:paddingright="@dimen/activity_horizontal_margin"     android:paddingtop="@dimen/activity_vertical_margin"     android:paddingbottom="@dimen/activity_vertical_margin"     tools:context=".mainactivity"     android:weightsum="1"     android:orientation="vertical">      <button         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="@string/add_button"         android:id="@+id/add_button"         android:layout_gravity="bottom"         android:onclick="ongetrecipeclick"/>      <listview         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:id="@+id/recipe_name_list"         android:layout_margintop="20dp"         android:background="#000000" /> </linearlayout> 

second_layout.xml

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:orientation="vertical"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:padding="20dp">          <edittext             android:layout_width="250dp"             android:layout_height="wrap_content"             android:id="@+id/recipe_name_edit_text"/>          <button             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:text="@string/enter_recipe_button_text"             android:id="@+id/save_button"             android:onclick="onsendrecipename"/>  </linearlayout> 

mainactivity.java

package com.jamielammas.recipeexample;  import android.content.intent; import android.os.bundle; import android.support.v7.app.actionbaractivity; import android.view.view; import android.widget.arrayadapter; import android.widget.listview;  public class mainactivity extends actionbaractivity {      public static listview listview;     public static arrayadapter adapter;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);     }      public void ongetrecipeclick(view view) {         intent getrecipescreenintent;         getrecipescreenintent = new intent(this, secondscreen.class);         final int result = 1;         getrecipescreenintent.putextra("callingactivity", "mainactivity");         startactivityforresult(getrecipescreenintent, result);     }      @override     protected void onactivityresult(int requestcode, int resultcode, intent data) {         super.onactivityresult(requestcode, resultcode, data);          listview = (listview) findviewbyid(r.id.recipe_name_list);         adapter = new arrayadapter<>(getapplicationcontext(), android.r.layout.simple_list_item_1, secondscreen.stringarray);         listview.setadapter(adapter);          adapter.notifydatasetchanged();     } } 

secondscreen.java

package com.jamielammas.recipeexample;  import android.app.activity; import android.content.intent; import android.os.bundle; import android.view.view; import android.widget.edittext;  import java.util.arraylist;  public class secondscreen extends activity {      public static edittext edittext;     public static arraylist<string> stringarray;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.second_layout);     }      public void onsendrecipename(view view) {          edittext = (edittext) findviewbyid(r.id.recipe_name_edit_text);          stringarray = new arraylist<>();         stringarray.add(secondscreen.edittext.gettext().tostring());          intent goingback = new intent();         setresult(result_ok, goingback);         finish();     } } 

any appreciated!

you can this:

secondscreen

 public void onsendrecipename(view view) {     edittext = (edittext) findviewbyid(r.id.recipe_name_edit_text);     intent goingback = new intent();     goingback.putextra("newitem",edittext.gettext().tostring());     setresult(result_ok, goingback);     finish(); } 

mainactivity

arraylist<string> arrayusedtocreatetheadapter = new arraylist<>();   @override protected void onactivityresult(int requestcode, int resultcode, intent data) {     super.onactivityresult(requestcode, resultcode, data);     if(resultcode == result_ok && data.hasextra("newitem")){        arrayusedtocreatetheadapter.add(data.getstringextra("newitem"););        adapter.notifydatasetchanged();     } }