Sunday, February 12, 2017

android - Volley JSON Array request example

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/coordinator_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#f1d9fc"
    >
    <Button
        android:id="@+id/btn_do"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Request JSON Array"
        android:layout_margin="25dp"
        android:layout_gravity="top|center_horizontal"
        />
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/btn_do"
        app:layout_anchorGravity="bottom"
        android:layout_gravity="bottom|center_horizontal"
        android:layout_margin="15dp"
        android:textSize="23sp"
        android:fontFamily="sans-serif"
        />
</android.support.design.widget.CoordinatorLayout>
MainActivity.java

package com.cfsuman.me.androidcodesnippets;

import android.app.Activity;
import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;


public class MainActivity extends AppCompatActivity {
    private Context mContext;
    private Activity mActivity;

    private CoordinatorLayout mCLayout;
    private Button mButtonDo;
    private TextView mTextView;
    private String mJSONURLString = "http://pastebin.com/raw/Em972E5s";


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

        // Get the application context
        mContext = getApplicationContext();
        mActivity = MainActivity.this;

        // Get the widget reference from XML layout
        mCLayout = (CoordinatorLayout) findViewById(R.id.coordinator_layout);
        mButtonDo = (Button) findViewById(R.id.btn_do);
        mTextView = (TextView) findViewById(R.id.tv);

        // Set a click listener for button widget
        mButtonDo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // Empty the TextView
                mTextView.setText("");

                // Initialize a new RequestQueue instance
                RequestQueue requestQueue = Volley.newRequestQueue(mContext);

                // Initialize a new JsonArrayRequest instance
                JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(
                        Request.Method.GET,
                        mJSONURLString,
                        null,
                        new Response.Listener<JSONArray>() {
                            @Override
                            public void onResponse(JSONArray response) {
                                // Do something with response
                                //mTextView.setText(response.toString());

                                // Process the JSON
                                try{
                                    // Loop through the array elements
                                    for(int i=0;i<response.length();i++){
                                        // Get current json object
                                        JSONObject student = response.getJSONObject(i);

                                        // Get the current student (json object) data
                                        String firstName = student.getString("firstname");
                                        String lastName = student.getString("lastname");
                                        String age = student.getString("age");

                                        // Display the formatted json data in text view
                                        mTextView.append(firstName +" " + lastName +"\nAge : " + age);
                                        mTextView.append("\n\n");
                                    }
                                }catch (JSONException e){
                                    e.printStackTrace();
                                }
                            }
                        },
                        new Response.ErrorListener(){
                            @Override
                            public void onErrorResponse(VolleyError error){
                                // Do something when error occurred
                                Snackbar.make(
                                        mCLayout,
                                        "Error...",
                                        Snackbar.LENGTH_LONG
                                ).show();
                            }
                        }
                );

                // Add JsonArrayRequest to the RequestQueue
                requestQueue.add(jsonArrayRequest);
            }
        });
    }
}
build.gradle(app) dependencies

compile 'com.android.volley:volley:1.0.0'