Improved Validate error messages

Filter the Validate class out of ValidationExceptions, to make it simpler to identify where the validation error originated.

Made malformed URL and empty selection error messages more explicit.

Simplified raising errors for null and empty parameters.

Author: jhy

CHANGES

@@ -4,6 +4,11 @@ Release 1.15.3 [PENDING]
   * Improvement: the Cleaner will preserve the source position of cleaned elements, if source tracking is enabled in the
     original parse.
 
+  * Improvement: the error messages output from Validate are more descriptive. Exceptions are now ValidationExceptions
+    (extending IllegalArgumentException). Stack traces do not include the Validate class, to make it simpler to see
+    where the exception originated. Common validation errors including malformed URLs and empty selector results have
+    more explicit error messages.
+
   * Bugfix: the DataUtil would incorrectly read from InputStreams that emitted reads less than the requested size. This
     lead to incorrect results when parsing from chunked server responses, for e.g.
     <https://github.com/jhy/jsoup/issues/1807>

src/main/java/org/jsoup/helper/HttpConnection.java

@@ -179,11 +179,11 @@ public Connection url(URL url) {
     }
 
     public Connection url(String url) {
-        Validate.notEmpty(url, "Must supply a valid URL");
+        Validate.notEmptyParam(url, "url");
         try {
             req.url(new URL(encodeUrl(url)));
         } catch (MalformedURLException e) {
-            throw new IllegalArgumentException("Malformed URL: " + url, e);
+            throw new IllegalArgumentException(String.format("The supplied URL, '%s', is malformed. Make sure it is an absolute URL, and starts with 'http://' or 'https://'.", url), e);
         }
         return this;
     }
@@ -199,7 +199,7 @@ public Connection proxy(String host, int port) {
     }
 
     public Connection userAgent(String userAgent) {
-        Validate.notNull(userAgent, "User agent must not be null");
+        Validate.notNullParam(userAgent, "userAgent");
         req.header(USER_AGENT, userAgent);
         return this;
     }
@@ -220,7 +220,7 @@ public Connection followRedirects(boolean followRedirects) {
     }
 
     public Connection referrer(String referrer) {
-        Validate.notNull(referrer, "Referrer must not be null");
+        Validate.notNullParam(referrer, "referrer");
         req.header("Referer", referrer);
         return this;
     }
@@ -263,15 +263,15 @@ public Connection data(String key, String filename, InputStream inputStream, Str
     }
 
     public Connection data(Map<String, String> data) {
-        Validate.notNull(data, "Data map must not be null");
+        Validate.notNullParam(data, "data");
         for (Map.Entry<String, String> entry : data.entrySet()) {
             req.data(KeyVal.create(entry.getKey(), entry.getValue()));
         }
         return this;
     }
 
     public Connection data(String... keyvals) {
-        Validate.notNull(keyvals, "Data key value pairs must not be null");
+        Validate.notNullParam(keyvals, "keyvals");
         Validate.isTrue(keyvals.length %2 == 0, "Must supply an even number of key value pairs");
         for (int i = 0; i < keyvals.length; i += 2) {
             String key = keyvals[i];
@@ -284,15 +284,15 @@ public Connection data(String... keyvals) {
     }
 
     public Connection data(Collection<Connection.KeyVal> data) {
-        Validate.notNull(data, "Data collection must not be null");
+        Validate.notNullParam(data, "data");
         for (Connection.KeyVal entry: data) {
             req.data(entry);
         }
         return this;
     }
 
     public Connection.KeyVal data(String key) {
-        Validate.notEmpty(key, "Data key must not be empty");
+        Validate.notEmptyParam(key, "key");
         for (Connection.KeyVal keyVal : request().data()) {
             if (keyVal.key().equals(key))
                 return keyVal;
@@ -311,7 +311,7 @@ public Connection header(String name, String value) {
     }
 
     public Connection headers(Map<String,String> headers) {
-        Validate.notNull(headers, "Header map must not be null");
+        Validate.notNullParam(headers, "headers");
         for (Map.Entry<String,String> entry : headers.entrySet()) {
             req.header(entry.getKey(),entry.getValue());
         }
@@ -324,7 +324,7 @@ public Connection cookie(String name, String value) {
     }
 
     public Connection cookies(Map<String, String> cookies) {
-        Validate.notNull(cookies, "Cookie map must not be null");
+        Validate.notNullParam(cookies, "cookies");
         for (Map.Entry<String, String> entry : cookies.entrySet()) {
             req.cookie(entry.getKey(), entry.getValue());
         }
@@ -432,7 +432,7 @@ public URL url() {
         }
 
         public T url(URL url) {
-            Validate.notNull(url, "URL must not be null");
+            Validate.notNullParam(url, "url");
             this.url = punyUrl(url); // if calling url(url) directly, does not go through encodeUrl, so we punycode it explicitly. todo - should we encode here as well?
             return (T) this;
         }
@@ -442,13 +442,13 @@ public Method method() {
         }
 
         public T method(Method method) {
-            Validate.notNull(method, "Method must not be null");
+            Validate.notNullParam(method, "method");
             this.method = method;
             return (T) this;
         }
 
         public String header(String name) {
-            Validate.notNull(name, "Header name must not be null");
+            Validate.notNullParam(name, "name");
             List<String> vals = getHeadersCaseInsensitive(name);
             if (vals.size() > 0) {
                 // https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
@@ -460,7 +460,7 @@ public String header(String name) {
 
         @Override
         public T addHeader(String name, String value) {
-            Validate.notEmpty(name);
+            Validate.notEmptyParam(name, "name");
             //noinspection ConstantConditions
             value = value == null ? "" : value;
 
@@ -476,7 +476,7 @@ public T addHeader(String name, String value) {
 
         @Override
         public List<String> headers(String name) {
-            Validate.notEmpty(name);
+            Validate.notEmptyParam(name, "name");
             return getHeadersCaseInsensitive(name);
         }
 
@@ -530,14 +530,14 @@ private static boolean looksLikeUtf8(byte[] input) {
         }
 
         public T header(String name, String value) {
-            Validate.notEmpty(name, "Header name must not be empty");
+            Validate.notEmptyParam(name, "name");
             removeHeader(name); // ensures we don't get an "accept-encoding" and a "Accept-Encoding"
             addHeader(name, value);
             return (T) this;
         }
 
         public boolean hasHeader(String name) {
-            Validate.notEmpty(name, "Header name must not be empty");
+            Validate.notEmptyParam(name, "name");
             return !getHeadersCaseInsensitive(name).isEmpty();
         }
 
@@ -556,8 +556,8 @@ public boolean hasHeaderWithValue(String name, String value) {
         }
 
         public T removeHeader(String name) {
-            Validate.notEmpty(name, "Header name must not be empty");
-            Map.Entry<String, List<String>> entry = scanHeaders(name); // remove is case insensitive too
+            Validate.notEmptyParam(name, "name");
+            Map.Entry<String, List<String>> entry = scanHeaders(name); // remove is case-insensitive too
             if (entry != null)
                 headers.remove(entry.getKey()); // ensures correct case
             return (T) this;
@@ -600,24 +600,24 @@ private List<String> getHeadersCaseInsensitive(String name) {
         }
 
         public String cookie(String name) {
-            Validate.notEmpty(name, "Cookie name must not be empty");
+            Validate.notEmptyParam(name, "name");
             return cookies.get(name);
         }
 
         public T cookie(String name, String value) {
-            Validate.notEmpty(name, "Cookie name must not be empty");
-            Validate.notNull(value, "Cookie value must not be null");
+            Validate.notEmptyParam(name, "name");
+            Validate.notNullParam(value, "value");
             cookies.put(name, value);
             return (T) this;
         }
 
         public boolean hasCookie(String name) {
-            Validate.notEmpty(name, "Cookie name must not be empty");
+            Validate.notEmptyParam(name, "name");
             return cookies.containsKey(name);
         }
 
         public T removeCookie(String name) {
-            Validate.notEmpty(name, "Cookie name must not be empty");
+            Validate.notEmptyParam(name, "name");
             cookies.remove(name);
             return (T) this;
         }
@@ -749,7 +749,7 @@ public Connection.Request ignoreContentType(boolean ignoreContentType) {
         }
 
         public Request data(Connection.KeyVal keyval) {
-            Validate.notNull(keyval, "Key val must not be null");
+            Validate.notNullParam(keyval, "keyval");
             data.add(keyval);
             return this;
         }
@@ -778,7 +778,7 @@ public Parser parser() {
         }
 
         public Connection.Request postDataCharset(String charset) {
-            Validate.notNull(charset, "Charset must not be null");
+            Validate.notNullParam(charset, "charset");
             if (!Charset.isSupported(charset)) throw new IllegalCharsetNameException(charset);
             this.postDataCharset = charset;
             return this;
@@ -834,7 +834,7 @@ static Response execute(HttpConnection.Request req, @Nullable Response previousR
                 Validate.isFalse(req.executing, "Multiple threads were detected trying to execute the same request concurrently. Make sure to use Connection#newRequest() and do not share an executing request between threads.");
                 req.executing = true;
             }
-            Validate.notNull(req, "Request must not be null");
+            Validate.notNullParam(req, "req");
             URL url = req.url();
             Validate.notNull(url, "URL must be specified to connect");
             String protocol = url.getProtocol();
@@ -1275,14 +1275,14 @@ public static KeyVal create(String key, String filename, InputStream stream) {
         }
 
         private KeyVal(String key, String value) {
-            Validate.notEmpty(key, "Data key must not be empty");
-            Validate.notNull(value, "Data value must not be null");
+            Validate.notEmptyParam(key, "key");
+            Validate.notNullParam(value, "value");
             this.key = key;
             this.value = value;
         }
 
         public KeyVal key(String key) {
-            Validate.notEmpty(key, "Data key must not be empty");
+            Validate.notEmptyParam(key, "key");
             this.key = key;
             return this;
         }
@@ -1292,7 +1292,7 @@ public String key() {
         }
 
         public KeyVal value(String value) {
-            Validate.notNull(value, "Data value must not be null");
+            Validate.notNullParam(value, "value");
             this.value = value;
             return this;
         }
@@ -1302,7 +1302,7 @@ public String value() {
         }
 
         public KeyVal inputStream(InputStream inputStream) {
-            Validate.notNull(value, "Data input stream must not be null");
+            Validate.notNullParam(value, "inputStream");
             this.stream = inputStream;
             return this;
         }