Add string utils repeat chars x times

src/changes/changes.xml

@@ -581,6 +581,7 @@ The <action> type attribute can be add,update,fix,remove.
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add JavaVersion.JAVA_17.</action>
     <action issue="LANG-1636" type="add" dev="ggregory" due-to="">Add missing boolean[] join method #686.</action>
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add StringUtils.substringBefore(String, int).</action>
+    <action                   type="add" dev="trungpnt" due-to="Trung Pham">Add StringUtils.resizeConsecutiveChars(String, char, int, boolean, boolean).</action>
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add Range.INTEGER.</action>
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add DurationUtils.</action>
     <action                   type="add" dev="jochen">Introduce the use of @Nonnull, and @Nullable, and the Objects class as a helper tool.</action>

src/main/java/org/apache/commons/lang3/StringUtils.java

@@ -9287,6 +9287,44 @@ public static String wrapIfMissing(final String str, final String wrapWith) {
         return builder.toString();
     }
 
+    public static String repeatChars(String str, Set<Character> appointedChars, Integer repetitions, boolean isResizeOnlyConsecutive) {
+        if (str == null || str.isEmpty()) {
+            return str;
+        }
+        final int xTimes = repetitions != null ? repetitions : 1;
+        final int len = str.length();
+        final int nbrOfCharsToResize = appointedChars.size();
+        final int newOutputMaxPossibleLen = (nbrOfCharsToResize * xTimes) + len;
+        final char[] collector = new char[newOutputMaxPossibleLen];
+        int collectorIdx = 0;
+        for (int i = 0; i < len; i++) {
+            final char current = str.charAt(i);
+            if (appointedChars.contains(current)) {
+                int spanEnd = i + 1;
+                while (spanEnd < str.length() && current == str.charAt(spanEnd)) {
+                    spanEnd++;
+                }
+                if (spanEnd == i + 1) {
+                    collector[collectorIdx++] = current;
+                } else if (!isResizeOnlyConsecutive || spanEnd > i + 1) {
+                    int repetition = xTimes;
+                    while (repetition-- > 0) {
+                        collector[collectorIdx++] = current;
+                    }
+                }
+                i = spanEnd - 1;
+            } else {
+                collector[collectorIdx++] = current;
+            }
+        }
+        return new String(collector, 0, collectorIdx);
+    }
+
+    public static String ensureOneWhitespace(String str) {
+        return repeatChars(str, new HashSet<>(Collections.singletonList(' ')), 1, true);
+    }
+
+
     /**
      * {@link StringUtils} instances should NOT be constructed in
      * standard programming. Instead, the class should be used as

src/test/java/org/apache/commons/lang3/StringUtilsTest.java

@@ -33,8 +33,9 @@
 import java.nio.CharBuffer;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
 import java.util.Collections;
+import java.util.Arrays;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
@@ -3246,4 +3247,45 @@ public void testWrapIfMissing_StringString() {
         assertSame("ab/ab", StringUtils.wrapIfMissing("ab/ab", "ab"));
         assertSame("//x//", StringUtils.wrapIfMissing("//x//", "//"));
     }
+
+    @Test
+    public void repeatChars() {
+        /**
+         * Resize 1 consecutive characters in a string to a specified length.
+         */
+        assertEquals("1 1 1    1",StringUtils.repeatChars("11111 111111 111111    111111",new HashSet<>(Collections.singletonList('1')),1,true));
+        assertEquals("aabbbcc",StringUtils.repeatChars("aaabbbcc",new HashSet<>(Collections.singletonList('a')),2,true));
+        assertEquals("1",StringUtils.repeatChars("111111",new HashSet<>(Collections.singletonList('1')),null,true));
+        assertEquals(".$$$42.1424.1.2.5.12.$!@.$!@%$.",StringUtils.repeatChars(".....$$$42....1424.1.....2.5.12..$!@..$!@%$...",new HashSet<>(Arrays.asList('.')),1,true));
+        assertEquals(".$$$42.1424.1.2.5.12.$!@.$!@%$.",StringUtils.repeatChars(".....$$$42....1424.1.....2.5.12..$!@..$!@%$...",new HashSet<>(Arrays.asList('.')),1,false));
+        assertEquals("1ewjaoij1 a1w1e1o1iw1 1213121 1",StringUtils.repeatChars("1ewjaoij1 a11w11111e11o11iw11 12113121 1",new HashSet<>(Arrays.asList('1')),1,true));
+        /**
+         * Resize to 2 repetitions with multiple consecutive characters.
+         */
+        assertEquals("11 11 11    11",StringUtils.repeatChars("11111 111111 111111    111111",new HashSet<>(Collections.singletonList('1')),2,true));
+        assertEquals("11 22 33   44",StringUtils.repeatChars("11111 222222 333333   444",new HashSet<>(Arrays.asList('1','2','3','4')),2,true));
+        assertEquals("11 22342422 33   44",StringUtils.repeatChars("11111 223424222 333333   444",new HashSet<>(Arrays.asList('1','2','3','4')),2,true));
+        assertEquals("1234",StringUtils.repeatChars("1234",new HashSet<>(Arrays.asList('1','2','3','4')),2,true));
+        assertEquals("11234",StringUtils.repeatChars("111111234",new HashSet<>(Arrays.asList('1','2','3','4')),2,true));
+        assertEquals("23411111",StringUtils.repeatChars("23411",new HashSet<>(Arrays.asList('1','2','3','4')),5,true));
+
+        // resizes whitespaces trimming
+        assertNull(StringUtils.ensureOneWhitespace(null));
+        assertEquals("",StringUtils.ensureOneWhitespace(""));
+        assertEquals(" ",StringUtils.ensureOneWhitespace("   "));
+        assertEquals("Hello",StringUtils.ensureOneWhitespace("Hello"));
+        assertEquals("Hello,World!",StringUtils.ensureOneWhitespace("Hello,World!"));
+        assertEquals("Hello,World!",StringUtils.ensureOneWhitespace("Hello,  World!"));
+        assertEquals("a a ",StringUtils.ensureOneWhitespace("a  a       "));
+        assertEquals(" a c b ncw a c j j j j j",StringUtils.ensureOneWhitespace("  a   c b  ncw   a  c j j j j      j"));
+        // resizes whitespaces without trimming
+        assertNull(StringUtils.ensureOneWhitespace(null));
+        assertEquals("",StringUtils.ensureOneWhitespace(""));
+        assertEquals(" ",StringUtils.ensureOneWhitespace("   "));
+        assertEquals("Hello",StringUtils.ensureOneWhitespace("Hello"));
+        assertEquals(" a b c ",StringUtils.ensureOneWhitespace("  a   b  c  "));
+        assertEquals(" Hello,World! ",StringUtils.ensureOneWhitespace(" Hello,   World! "));
+        assertEquals("Hello,World!",StringUtils.ensureOneWhitespace("Hello,  World!"));
+        assertEquals(" a a ",StringUtils.ensureOneWhitespace(" a  a       "));
+    }
 }