dependencies {
    implementation 'com.google.android.gms:play-services-safetynet:15.0.1'
    implementation 'com.android.volley:volley:1.0.0'
}

package example.javatpoint.com.googlerecaptcha;

import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.android.volley.DefaultRetryPolicy;
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.StringRequest;
import com.android.volley.toolbox.Volley;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.common.api.CommonStatusCodes;
import com.google.android.gms.safetynet.SafetyNet;
import com.google.android.gms.safetynet.SafetyNetApi;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    String TAG = MainActivity.class.getSimpleName();
    Button btnverifyCaptcha;
    String SITE_KEY = "6LeaN24UAxxxxx_YOUR_SITE_KEY";
    String SECRET_KEY = "6LeaN24UAxxxxx_YOUR_SECRET_KEY";
    RequestQueue queue;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnverifyCaptcha = findViewById(R.id.button);
        btnverifyCaptcha.setOnClickListener(this);

        queue = Volley.newRequestQueue(getApplicationContext());
    }

    @Override
    public void onClick(View view) {
        SafetyNet.getClient(this).verifyWithRecaptcha(SITE_KEY)
                .addOnSuccessListener(this, new OnSuccessListener() {
                    @Override
                    public void onSuccess(SafetyNetApi.RecaptchaTokenResponse response) {
                        if (!response.getTokenResult().isEmpty()) {
                            handleSiteVerify(response.getTokenResult());
                        }
                    }
                })
                .addOnFailureListener(this, new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        if (e instanceof ApiException) {
                            ApiException apiException = (ApiException) e;
                            Log.d(TAG, "Error message: " +
                                    CommonStatusCodes.getStatusCodeString(apiException.getStatusCode()));
                        } else {
                            Log.d(TAG, "Unknown type of error: " + e.getMessage());
                        }
                    }
                });

    }
    protected  void handleSiteVerify(final String responseToken){
        //it is google recaptcha siteverify server
        //you can place your server url
        String url = "https://www.google.com/recaptcha/api/siteverify";
        StringRequest request = new StringRequest(Request.Method.POST, url,
                new Response.Listener() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            JSONObject jsonObject = new JSONObject(response);
                            if(jsonObject.getBoolean("success")){
                                //code logic when captcha returns true Toast.makeText(getApplicationContext(),String.valueOf(jsonObject.getBoolean("success")),Toast.LENGTH_LONG).show();
                            }
                            else{
                                Toast.makeText(getApplicationContext(),String.valueOf(jsonObject.getString("error-codes")),Toast.LENGTH_LONG).show();
                            }
                        } catch (Exception ex) {
                            Log.d(TAG, "JSON exception: " + ex.getMessage());

                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.d(TAG, "Error message: " + error.getMessage());
                    }
                }) {
            @Override
            protected Map getParams() {
                Map params = new HashMap<>();
                params.put("secret", SECRET_KEY);
                params.put("response", responseToken);
                return params;
            }
        };
        request.setRetryPolicy(new DefaultRetryPolicy(
                50000,
                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
        queue.add(request);
    }
}