implement more string util functions

Author: rbri

src/main/java/org/htmlunit/util/StringUtils.java

@@ -70,6 +70,77 @@ public static boolean isEmptyString(final CharSequence s) {
         return s != null && s.length() == 0;
     }
 
+    /**
+     * Returns true if the param is null or empty.
+     *
+     * @param s the string to check
+     * @return true if the param is null or empty
+     */
+    public static boolean isEmptyOrNull(final CharSequence s) {
+        return s == null || s.length() == 0;
+    }
+
+    /**
+     * Returns either the passed in CharSequence, or if the CharSequence is
+     * empty or {@code null}, the default value.
+     *
+     * @param <T> the kind of CharSequence
+     * @param s  the CharSequence to check
+     * @param defaultString the default to return if the input is empty or null
+     * @return the passed in CharSequence, or the defaultString
+     */
+    public static <T extends CharSequence> T defaultIfEmptyOrNull(final T s, final T defaultString) {
+        return isEmptyOrNull(s) ? defaultString : s;
+    }
+
+    /**
+     * Tests if a CharSequence is null, empty, or contains only whitespace.
+     *
+     * @param s the CharSequence to check
+     * @return true if a CharSequence is null, empty, or contains only whitespace
+     */
+    public static boolean isBlank(final CharSequence s) {
+        if (s == null) {
+            return true;
+        }
+
+        final int length = s.length();
+        if (length == 0) {
+            return true;
+        }
+
+        for (int i = 0; i < length; i++) {
+            if (!Character.isWhitespace(s.charAt(i))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Tests if a CharSequence is NOT null, empty, or contains only whitespace.
+     *
+     * @param s the CharSequence to check
+     * @return false if a CharSequence is null, empty, or contains only whitespace
+     */
+    public static boolean isNotBlank(final CharSequence s) {
+        if (s == null) {
+            return false;
+        }
+
+        final int length = s.length();
+        if (length == 0) {
+            return false;
+        }
+
+        for (int i = 0; i < length; i++) {
+            if (!Character.isWhitespace(s.charAt(i))) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     /**
      * @param expected the char that we expect
      * @param s the string to check
@@ -687,7 +758,7 @@ public static String[] splitAtComma(final String str) {
      * Splits the provided text into an array, using comma or blank as the
      * separator.
      *
-     * @param str  the String to parse, may be null
+     * @param str the String to parse, may be null
      * @return an array of parsed Strings, an empty array if null String input
      */
     public static String[] splitAtCommaOrBlank(final String str) {

src/test/java/org/htmlunit/util/StringUtilsTest.java

@@ -45,6 +45,67 @@ public void isEmptyString() throws Exception {
         assertFalse(StringUtils.isEmptyString("string"));
     }
 
+    /**
+     * @throws Exception if the test fails
+     */
+    @Test
+    public void isEmptyOrNull() throws Exception {
+        assertTrue(StringUtils.isEmptyOrNull(null));
+        assertTrue(StringUtils.isEmptyOrNull(""));
+        assertFalse(StringUtils.isEmptyOrNull(" "));
+        assertFalse(StringUtils.isEmptyOrNull("\t"));
+        assertFalse(StringUtils.isEmptyOrNull("\r"));
+        assertFalse(StringUtils.isEmptyOrNull("\n"));
+        assertFalse(StringUtils.isEmptyOrNull("string"));
+    }
+
+
+    /**
+     * @throws Exception if the test fails
+     */
+    @Test
+    public void defaultIfEmptyOrNull() throws Exception {
+        assertEquals("X", StringUtils.defaultIfEmptyOrNull(null, "X"));
+        assertEquals("X", StringUtils.defaultIfEmptyOrNull("", "X"));
+
+        assertEquals(" ", StringUtils.defaultIfEmptyOrNull(" ", "X"));
+        assertEquals("a", StringUtils.defaultIfEmptyOrNull("a", "X"));
+    }
+
+    /**
+     * @throws Exception if the test fails
+     */
+    @Test
+    public void isBlank() throws Exception {
+        assertTrue(StringUtils.isBlank(null));
+        assertTrue(StringUtils.isBlank(""));
+        assertTrue(StringUtils.isBlank(" "));
+        assertTrue(StringUtils.isBlank("\t"));
+        assertTrue(StringUtils.isBlank("\r"));
+        assertTrue(StringUtils.isBlank("\n"));
+
+        assertFalse(StringUtils.isBlank("x"));
+        assertFalse(StringUtils.isBlank("string"));
+        assertFalse(StringUtils.isBlank("    x"));
+    }
+
+    /**
+     * @throws Exception if the test fails
+     */
+    @Test
+    public void isNotBlank() throws Exception {
+        assertFalse(StringUtils.isNotBlank(null));
+        assertFalse(StringUtils.isNotBlank(""));
+        assertFalse(StringUtils.isNotBlank(" "));
+        assertFalse(StringUtils.isNotBlank("\t"));
+        assertFalse(StringUtils.isNotBlank("\r"));
+        assertFalse(StringUtils.isNotBlank("\n"));
+
+        assertTrue(StringUtils.isNotBlank("x"));
+        assertTrue(StringUtils.isNotBlank("string"));
+        assertTrue(StringUtils.isNotBlank("    x"));
+    }
+
     /**
      * @throws Exception if the test fails
      */