fix javadoc errors

fix 50% of the warnings

Author: jvmvik

src/main/java/serpapi/BaiduSearch.java

@@ -8,24 +8,38 @@
  *
  * Usage 
  * --- 
- * ```java 
+ * <pre>
+ * {@code 
  * Map<String, String> parameter = new HashMap<>();
  * parameter.put("q", "Coffee");
  * BaiduSearch baidu = new BaiduSearch(parameter, "secret api key"); 
  * JsonObject data = baidu.getJson();
  * JsonArray organic_results = data.get("organic_results").getAsJsonArray();
- * ```
+ * }
+ * </pre>
  */
 public class BaiduSearch extends SerpApiSearch {
 
+ /**
+  * Constructor
+  * @param parameter search parameter
+  * @param apiKey secret API key
+  */
   public BaiduSearch(Map<String, String> parameter, String apiKey) {
     super(parameter, apiKey, "baidu");
   }
 
+  /**
+   * Constructor
+   */
   public BaiduSearch() {
     super("baidu");
   }
 
+  /**
+  * Constructor
+  * @param parameter search parameter
+  */
   public BaiduSearch(Map<String, String> parameter) {
     super(parameter, "baidu");
   }

src/main/java/serpapi/BingSearch.java

@@ -8,24 +8,38 @@
  *
  * Usage 
  * --- 
- * ```java 
+ * <pre>
+ * {@code 
  * Map<String, String> parameter = new HashMap<>();
  * parameter.put("q", "Coffee");
  * BingSearch bing = new BingSearch(parameter, "secret api key"); 
  * JsonObject data = bing.getJson();
  * JsonArray organic_results = data.get("organic_results").getAsJsonArray();
- * ```
+ * }
+ * </pre>
  */
 public class BingSearch extends SerpApiSearch {
 
+ /**
+  * Constructor
+  * @param parameter search parameter
+  * @param apiKey secret API key
+  */
   public BingSearch(Map<String, String> parameter, String apiKey) {
     super(parameter, apiKey, "bing");
   }
 
+  /**
+   * Constructor
+   */
   public BingSearch() {
     super("bing");
   }
 
+ /**
+  * Constructor
+  * @param parameter search parameter
+  */
   public BingSearch(Map<String, String> parameter) {
     super(parameter, "bing");
   }

src/main/java/serpapi/EbaySearch.java

@@ -8,24 +8,38 @@
  *
  * Usage 
  * --- 
- * ```java 
+ * <pre>
+ * {@code 
  * Map<String, String> parameter = new HashMap<>();
  * parameter.put("_nkw", "Coffee");
  * EbaySearch ebay = new EbaySearch(parameter, "secret api key"); 
  * JsonObject data = ebay.getJson();
  * JsonArray organic_results = data.get("organic_results").getAsJsonArray();
- * ```
+ * }
+ * </pre>
  */
 public class EbaySearch extends SerpApiSearch {
 
+ /**
+  * Constructor
+  * @param parameter search parameter
+  * @param apiKey secret API key
+  */
   public EbaySearch(Map<String, String> parameter, String apiKey) {
     super(parameter, apiKey, "ebay");
   }
 
+  /**
+   * Constructor
+   */
   public EbaySearch() {
     super("ebay");
   }
 
+  /**
+  * Constructor
+  * @param parameter search parameter
+  */
   public EbaySearch(Map<String, String> parameter) {
     super(parameter, "ebay");
   }

src/main/java/serpapi/GoogleSearch.java

@@ -8,24 +8,38 @@
  *
  * Usage 
  * --- 
- * ```java 
+ * <pre>
+ * {@code 
  * Map<String, String> parameter = new HashMap<>();
  * parameter.put("q", "Coffee");
  * GoogleSearch google = new GoogleSearch(parameter, "secret api key"); 
  * JsonObject data = google.getJson();
  * JsonArray organic_results = data.get("organic_results").getAsJsonArray();
- * ```
+ * }
+ * </pre>
  */
 public class GoogleSearch extends SerpApiSearch {
 
+ /**
+  * Constructor
+  * @param parameter search parameter
+  * @param apiKey secret API key
+  */
   public GoogleSearch(Map<String, String> parameter, String apiKey) {
     super(parameter, apiKey, "google");
   }
 
+ /**
+  * Constructor
+  */
   public GoogleSearch() {
     super("google");
   }
 
+ /**
+  * Constructor
+  * @param parameter search parameter
+  */
   public GoogleSearch(Map<String, String> parameter) {
     super(parameter, "google");
   }

src/main/java/serpapi/ParameterStringBuilder.java

@@ -4,8 +4,15 @@
 import java.net.URLEncoder;
 import java.util.Map;
 
+/***
+ * Encode parameter hash into a string
+ *  to be sent over HTTP
+ */
 public class ParameterStringBuilder
  {
+   /***
+    * @param params search parameters
+    */
     public static String getParamsString(Map<String, String> params)
       throws UnsupportedEncodingException
     {

src/main/java/serpapi/SerpApiHttpClient.java

@@ -21,17 +21,21 @@ public class SerpApiHttpClient {
   private int httpConnectionTimeout;
   private int httpReadTimeout;
 
+  // current API version
   public static String VERSION = "2.0.1";
+
+  // backend service
   public static String BACKEND = "https://serpapi.com";
 
   // initialize gson
   private static Gson gson = new Gson();
 
-  // path
+  // current backend HTTP path
   public String path;
 
   /***
-   * @param String path
+   * Constructor
+   * @param path
    */
   public SerpApiHttpClient(String path) {
     this.path = path;
@@ -40,12 +44,12 @@ public SerpApiHttpClient(String path) {
   /***
    * Build URL
    *
-   * @param path  url end point
-   * @param param hash
+   * @param path url end point
+   * @param parameter search parameter map like: { "q": "coffee", "location": "Austin, TX"}
    * @return httpUrlConnection
-   * @throws IOException
+   * @throws SerpApiSearchException
    */
-  public HttpURLConnection buildConnection(String path, Map<String, String> parameter) throws SerpApiSearchException {
+  protected HttpURLConnection buildConnection(String path, Map<String, String> parameter) throws SerpApiSearchException {
     HttpURLConnection con;
     try {
       allowHTTPS();
@@ -115,7 +119,7 @@ public boolean verify(String hostname, SSLSession session) {
   /***
    * Get results
    *
-   * @param parameter
+   * @param parameter user search parameters
    * @return http response body
    */
   public String getResults(Map<String, String> parameter) throws SerpApiSearchException {
@@ -162,7 +166,7 @@ public String getResults(Map<String, String> parameter) throws SerpApiSearchExce
     return content.toString();
   }
 
-  public void triggerSerpApiClientException(String content) throws SerpApiSearchException {
+  protected void triggerSerpApiClientException(String content) throws SerpApiSearchException {
     String errorMessage;
     try {
       JsonObject element = gson.fromJson(content, JsonObject.class);
@@ -173,18 +177,30 @@ public void triggerSerpApiClientException(String content) throws SerpApiSearchEx
     throw new SerpApiSearchException(errorMessage);
   }
 
+  /**
+    * @return current HTTP connection timeout
+    */
   public int getHttpConnectionTimeout() {
     return httpConnectionTimeout;
   }
 
+  /**
+   * @param httpConnectionTimeout set HTTP connection timeout
+   */
   public void setHttpConnectionTimeout(int httpConnectionTimeout) {
     this.httpConnectionTimeout = httpConnectionTimeout;
   }
 
+  /**
+   * @return current HTTP read timeout
+   */
   public int getHttpReadTimeout() {
     return httpReadTimeout;
   }
 
+  /**
+   * @param httpReadTimeout set HTTP read timeout
+   */
   public void setHttpReadTimeout(int httpReadTimeout) {
     this.httpReadTimeout = httpReadTimeout;
   }