How to save data in a listView

Question

I created a listView that is based on the user input. User has to enter text in an editText and then it's added into the list. It works great. My question though, is how do I save this data so even when they close the app, and then open it back up again, the listView still has the items in it from last time? Here is my code:

MainActivity.java

    package com.kass.planner2;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

import java.util.ArrayList;

public class MainActivity extends Activity implements View.OnClickListener {

    private Button btn;
    private EditText et;
    private ListView lv;
    ArrayList<String> list = new ArrayList<String>();
    ArrayAdapter<String> adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn = (Button)findViewById(R.id.button);
        btn.setOnClickListener(this);
        et = (EditText)findViewById(R.id.editText);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, list);

        // set the lv variable to your list in the xml
        lv=(ListView)findViewById(R.id.listView);
        lv.setAdapter(adapter);
    }
    public void onClick(View v)
    {
        String input = et.getText().toString();
        if(input.length() > 0)
        {
            // add string to the adapter, not the listview
            adapter.add(input);
            // no need to call adapter.notifyDataSetChanged(); as it is done by the adapter.add() method
        }
    }


}

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="com.kass.planner2.MainActivity"
    android:weightSum="1">

    <RelativeLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true"
        android:layout_weight="1.12">

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/editText"
            android:layout_alignParentTop="true"
            android:layout_alignParentStart="true"
            android:layout_marginTop="60dp"
            android:layout_alignEnd="@+id/button" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="New Button"
            android:id="@+id/button"
            android:layout_centerVertical="true"
            android:layout_alignParentStart="true"
            android:onClick="saveEvent"/>

        <ListView
            android:layout_width="match_parent"
            android:layout_height="fill_parent"
            android:id="@+id/listView"
            android:layout_centerVertical="true"
            android:layout_alignParentEnd="true"
            android:layout_toEndOf="@+id/editText" />
    </RelativeLayout>


</LinearLayout>

Thank you.

Answer 1

If you don't want to use the database, here is a trick that might help you with using file handling with a little logic

public void writeData(String data)      // to writeData to file  
{
String fileName="listData.txt";
try {
        FileOutputStream fileout=openFileOutput(fileName, MODE_APPEND);
        OutputStreamWriter outputWriter=new OutputStreamWriter(fileout);
        outputWriter.write(data);
        outputWriter.close();



    } catch (Exception e) {
        e.printStackTrace();
    }    
 }

 public String readFile()
{
String fileName="listData.txt";
String line,data="";

try {
        FileInputStream fIn = openFileInput ( fileName ) ;
        InputStreamReader isr = new InputStreamReader ( fIn ) ;
        BufferedReader br = new BufferedReader ( isr ) ;

       while((line=br.readLine())!=null)
       {
         data=data+line;
       }

        isr.close ( ) ;
    } catch ( IOException ioe ) {
        ioe.printStackTrace ( ) ;
    }

    return data;
 }

Here are the methods to have to call

 public void storeData()      // call this in the onclick 
{
String res="";

res= res + editText().getText().toString() + "\n";    // used \n as     delimiter

writeData(res);

}

Now here is the trick. In the oncreate, call the splitIntoList() method , before creating the arrayadapter

public void splitIntoList()
{
String result=readFile();

//Here is a little logic

StringTokenizer st=new StringTokenizer(result,"\n");
while(st.hasMoreTokens())
{
        list.add(st.nextToken());
}
}

Please check for errors because I haven't ran this code on the IDE

Answer 2

Considering you are still learning I suggest you start with using the SQLite methods. http://www.tutorialspoint.com/android/android_sqlite_database.htm

For a quicker and cleaner implementation you could use an ORM like SugarORM: http://satyan.github.io/sugar/

They have simple to follow commands that could be used to easy build databases and extract data from them.

Answer 3

Listview, as the name suggests is a View which can show data. It doesn't actually saves data. To save the data, you have to use a database or SharedPreferences. Normally shared preferences are used to save quick settings of the app.
To save data, you need to use the SQLite database present in each android device. This is done using SQLiteDatabase and SQLiteOpenHelper classes in android.
To bind the data to a view like a ListView which shows multiple data rows at once, you need to use an adapter. A SimpleCursorAdapter class does this job easily.
You can find a tutorial here for binding data to controls like TextView here. It will give you an idea of how to set up a database on your device.
Once you've done that, you can read about SimpleCursorAdapter here.