How to append data from priority queue to arraylist for listview in Android?

This example demonstrate about How to append data from priority queue to arraylist for listview in Android

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayoutxmlns:android = "https://schemas.android.com/apk/res/android"
   xmlns:tools = "https://schemas.android.com/tools"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   tools:context = ".MainActivity"
   android:orientation = "vertical">
   <EditText
      android:id = "@+id/name"
      android:layout_width = "match_parent"
      android:hint = "Enter Name"
      android:layout_height = "wrap_content" />
   <LinearLayout
      android:layout_width = "wrap_content"
      android:layout_height = "wrap_content">
      <Button
         android:id = "@+id/save"
         android:text = "Save"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content" />
      <Button
         android:id = "@+id/refresh"
         android:text = "Refresh"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content" />
   </LinearLayout>
   <ListView
      android:id = "@+id/listView"
      android:layout_width = "match_parent"
      android:layout_height = "wrap_content">
   </ListView>
</LinearLayout>

In the above code, we have taken name as Edit text, when user click on save button it will store the data into arraylist. Click on refresh button to get the changes of listview.

Step 3 − Add the following code to src/MainActivity.java

package com.example.andy.myapplication;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.PriorityQueue;
import java.util.TreeSet;
public class MainActivityextends AppCompatActivity {
   Button save, refresh;
   EditTextname;
   ArrayAdapterarrayAdapter;
   PriorityQueue<String>hs;
   ArrayList<String>array_list;
   private ListViewlistView;
   @Override
   protected void onCreate(Bundle readdInstanceState) {
      super.onCreate(readdInstanceState);
      setContentView(R.layout.activity_main);
      array_list = new ArrayList<>();
      name = findViewById(R.id.name);
      listView = findViewById(R.id.listView);
      findViewById(R.id.refresh).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            arrayAdapter.notifyDataSetChanged();
            listView.invalidateViews();
            listView.refreshDrawableState();
         }
      });
      findViewById(R.id.save).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (!name.getText().toString().isEmpty()) {
               array_list.add(name.getText().toString());
               PriorityQueue<String>hs = new PriorityQueue<String>();
               hs.addAll(array_list);
               array_list.clear();
               array_list.addAll(hs);
               arrayAdapter = new ArrayAdapter(MainActivity.this, android.R.layout.simple_list_item_1, array_list);
               listView.setAdapter(arrayAdapter);
               Toast.makeText(MainActivity.this, "Inserted", Toast.LENGTH_LONG).show();
            } else {
               name.setError("Enter NAME");
            }
         }
      });
   }
}

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –

In the above result, we are inserting name of priority queue to arraylist.