GINPRO / SQLの窓と銀プログラマ

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.google.code.gson:gson:2.8.5'
    implementation 'com.squareup.okhttp3:okhttp:4.1.0'
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

public class Weather {

	WebData[] pinpointLocations;

}

public class WebData {

	String link;
	String name;

	@Override
	public String toString() {
		return name;
	}
}

import android.os.AsyncTask;

import java.io.IOException;

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class HttpAccess {

	private OkHttpClient okHttpClient;
	private String url;

	public interface OnAsyncTaskListener {
		abstract public void onAsyncTaskListener(String s);
	}

	public HttpAccess(String url) {
		this.okHttpClient = new OkHttpClient();
		this.url = url;
	}

	public void sendGet(final OnAsyncTaskListener listener ) {

		new AsyncTask<Void,Void,String>(){
			@Override
			protected String doInBackground(Void... params) {
				String result = "[\"error\"]";

				Request.Builder builder = new Request.Builder();
				builder.url(HttpAccess.this.url);
				Request request = builder.build();

				Response response = null;
				try {
					response = HttpAccess.this.okHttpClient.newCall(request).execute();
					result = response.body().string();
				}
				catch (IOException e) {
					e.printStackTrace();
				}

				return result;
			}

			// UI スレッド処理
			@Override
			protected void onPostExecute(String s) {
				super.onPostExecute(s);

				listener.onAsyncTaskListener(s);

			}
		}.execute();

	}

}

private ListView listView;
private ArrayAdapter<WebData> arrayAdapter;
private HttpAccess httpAccess;

listView = (ListView) MainActivity.this.findViewById(R.id.listView);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
	public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

		// クリックされたアイテムを取得
		WebData mydata = (WebData) parent.getItemAtPosition(position);
		// LogCatに表示
		Log.i("lightbox", mydata.name);
		Log.i("lightbox", mydata.link);

		// URL を開く
		Uri uri = Uri.parse(mydata.link);
		Intent intent = new Intent(Intent.ACTION_VIEW, uri);
		if (intent.resolveActivity(MainActivity.this.getPackageManager()) != null) {
			MainActivity.this.startActivity(intent);
			return;
		}

	}
});
arrayAdapter = new ArrayAdapter<WebData>(MainActivity.this,android.R.layout.simple_list_item_1);

new HttpAccess("https://your-project-xxxxx.firebaseio.com/weather.json")
	.sendGet(new HttpAccess.OnAsyncTaskListener() {
		@Override
		public void onAsyncTaskListener(String s) {

			Gson gson = new Gson();
			Weather weather = gson.fromJson(s, Weather.class);

			arrayAdapter.clear();
			arrayAdapter.addAll(weather.pinpointLocations);

		}
	});