Example code to search Google Plus public posts

package com.exercise.AndroidGooglePlus;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;

import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidGooglePlusActivity extends Activity {
 
 
 TextView item_post;
 
 final static String GeogleApisUrl = "https://www.googleapis.com/plus/v1/";
 final static String API_KEY = "<Your API key>";
 
 final static String GooglePlusPublicPosts_url
 = GeogleApisUrl
 + "activities?query=cookie%20recipes&orderBy=best"
 + "&key=" + API_KEY;
 
 String[] PublicPosts = null;
 
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  
  item_post = (TextView)findViewById(R.id.item_post); 
  
  String googlePlusResult = QueryGooglePlus(GooglePlusPublicPosts_url);
  ParseGooglePlusJSON_PublicPosts(googlePlusResult); 
  
 }
 
 String QueryGooglePlus(String queryString){
  String qResult = null;
  
  HttpClient httpClient = new DefaultHttpClient();
  HttpGet httpGet = new HttpGet(queryString);
    
  try {
   HttpEntity httpEntity = httpClient.execute(httpGet).getEntity();
   
   if (httpEntity != null){
    InputStream inputStream = httpEntity.getContent();
    Reader in = new InputStreamReader(inputStream);
    BufferedReader bufferedreader = new BufferedReader(in);
    StringBuilder stringBuilder = new StringBuilder();
    
    String stringReadLine = null;
    
    while ((stringReadLine = bufferedreader.readLine()) != null) {
     stringBuilder.append(stringReadLine + "\n");  
    }
    
    qResult = stringBuilder.toString();  
   }  
  } catch (ClientProtocolException e) {
   e.printStackTrace();
   Toast.makeText(AndroidGooglePlusActivity.this,
     e.toString(),
     Toast.LENGTH_LONG).show(); 
  } catch (IOException e) {
   e.printStackTrace();
   Toast.makeText(AndroidGooglePlusActivity.this,
     e.toString(),
     Toast.LENGTH_LONG).show(); 
  }
  return qResult; 
 }
 
 void ParseGooglePlusJSON_PublicPosts(String json){
  if(json != null){
   
   try {
    JSONObject JsonObject = new JSONObject(json);
    
    JSONArray JsonArray_items = JsonObject.getJSONArray("items");
    
    PublicPosts = new String[JsonArray_items.length()];
    for (int i = 0; i < JsonArray_items.length(); i++){
     JSONObject post = JsonArray_items.getJSONObject(i);
     PublicPosts[i] = post.getString("title");
    }
    
    String postList = "";
    for (int i = 0; i < PublicPosts.length; i++){
     postList += String.valueOf(i) + ": " + PublicPosts[i] + "\n"
       + "------------\n";
    }
    item_post.setText(postList);
          
             Toast.makeText(AndroidGooglePlusActivity.this,
               "finished",
               Toast.LENGTH_LONG).show(); 
   } catch (JSONException e) {
    e.printStackTrace();
    Toast.makeText(AndroidGooglePlusActivity.this,
      e.toString(),
      Toast.LENGTH_LONG).show(); 
   } 
  } 
 }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<TextView
android:id="@+id/item_post"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

Note: Need permission of "android.permission.INTERNET" to access Google Plus online.

Download the files.

Ref:
- Google+ Platform Blog - Google+ APIs: Now With Search and More!

Related article:
- Query and Parse Google+ JSON