Monday, August 10, 2015

How to remove all items from ListView in Android

MainActivity.java

package com.cfsuman.androidtutorials;

import android.os.Bundle;
import android.app.Activity;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Get the widgets reference from XML layout
        Button button = findViewById(R.id.button);
        ListView listView = findViewById(R.id.listView);

        // Initializing a new String Array
        String[] fruits = new String[] {
                "Black Walnut",
                "Blackberry",
                "Blue tongue",
                "Bolwarra",
                "Bottle Gourd"
        };

        // Create a List from String Array elements
        final List<String> fruits_list = new ArrayList<String>
                (Arrays.asList(fruits));

        // Create an ArrayAdapter from List
        final ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>
                (
                    this,
                    android.R.layout.simple_list_item_1,
                    fruits_list
                );

        // DataBind ListView with items from ArrayAdapter
        listView.setAdapter(arrayAdapter);

        button.setOnClickListener(view -> {
            // Remove / Delete all items from List
            // Clear ListView Items
            fruits_list.clear();
            /*
                notifyDataSetChanged ()
                    Notifies the attached observers that the underlying
                    data has been changed and any View reflecting the
                    data set should refresh itself.
             */
            arrayAdapter.notifyDataSetChanged();

            // Disable the button itself
            view.setEnabled(false);
        });
    }
}
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DCDCDC"
    android:padding="24dp">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Remove All Items From ListView"
        android:textAllCaps="false"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

</androidx.constraintlayout.widget.ConstraintLayout>