BAEL-5550: Trim a string based on the string length

core-java-modules/core-java-string-operations-4/src/main/java/com/baeldung/truncate/TruncateString.java

@@ -0,0 +1,105 @@
+package com.baeldung.truncate;
+
+import java.util.Optional;
+import java.util.regex.MatchResult;
+import java.util.regex.Pattern;
+
+import org.apache.commons.lang3.StringUtils;
+
+import com.google.common.base.Splitter;
+
+public class TruncateString {
+
+    private static final String EMPTY = "";
+
+    public static String usingSubstringMethod(String text, int length) {
+        if (length < 0) {
+            throw new IllegalArgumentException("length cannot be negative");
+        }
+
+        if (text == null) {
+            return EMPTY;
+        }
+
+        if (text.length() <= length) {
+            return text;
+        } else {
+            return text.substring(0, length);
+        }
+    }
+
+    public static String usingSplitMethod(String text, int length) {
+        if (length < 0) {
+            throw new IllegalArgumentException("length cannot be negative");
+        }
+
+        if (text == null) {
+            return EMPTY;
+        }
+
+        String[] results = text.split("(?<=\\G.{" + length + "})");
+
+        return results[0];
+    }
+
+    public static String usingPattern(String text, int length) {
+        if (length < 0) {
+            throw new IllegalArgumentException("length cannot be negative");
+        }
+
+        if (text == null) {
+            return EMPTY;
+        }
+
+        Optional<String> result = Pattern.compile(".{1," + length + "}")
+            .matcher(text)
+            .results()
+            .map(MatchResult::group)
+            .findFirst();
+
+        return result.isPresent() ? result.get() : EMPTY;
+
+    }
+
+    public static String usingCodePointsMethod(String text, int length) {
+        if (length < 0) {
+            throw new IllegalArgumentException("length cannot be negative");
+        }
+
+        if (text == null) {
+            return EMPTY;
+        }
+
+        return text.codePoints()
+            .limit(length)
+            .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
+            .toString();
+    }
+
+    public static String usingLeftMethod(String text, int length) {
+
+        return StringUtils.left(text, length);
+    }
+
+    public static String usingTruncateMethod(String text, int length) {
+
+        return StringUtils.truncate(text, length);
+    }
+
+    public static String usingSplitter(String text, int length) {
+        if (length < 0) {
+            throw new IllegalArgumentException("length cannot be negative");
+        }
+
+        if (text == null) {
+            return EMPTY;
+        }
+
+        Iterable<String> parts = Splitter.fixedLength(length)
+            .split(text);
+
+        return parts.iterator()
+            .next();
+    }
+
+}

core-java-modules/core-java-string-operations-4/src/test/java/com/baeldung/truncate/TruncateStringUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.truncate;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class TruncateStringUnitTest {
+
+    private static final String TEXT = "Welcome to baeldung.com";
+
+    @Test
+    public void givenStringAndLength_whenUsingSubstringMethod_thenTruncate() {
+
+        assertEquals(TruncateString.usingSubstringMethod(TEXT, 10), "Welcome to");
+    }
+
+    @Test
+    public void givenStringAndLength_whenUsingSplitMethod_thenTruncate() {
+
+        assertEquals(TruncateString.usingSplitMethod(TEXT, 13), "Welcome to ba");
+    }
+
+    @Test
+    public void givenStringAndLength_whenUsingPattern_thenTruncate() {
+
+        assertEquals(TruncateString.usingPattern(TEXT, 19), "Welcome to baeldung");
+    }
+
+    @Test
+    public void givenStringAndLength_whenUsingCodePointsMethod_thenTruncate() {
+
+        assertEquals(TruncateString.usingCodePointsMethod(TEXT, 6), "Welcom");
+    }
+
+    @Test
+    public void givenStringAndLength_whenUsingLeftMethod_thenTruncate() {
+
+        assertEquals(TruncateString.usingLeftMethod(TEXT, 15), "Welcome to bael");
+    }
+
+    @Test
+    public void givenStringAndLength_whenUsingTruncateMethod_thenTruncate() {
+
+        assertEquals(TruncateString.usingTruncateMethod(TEXT, 20), "Welcome to baeldung.");
+    }
+
+    @Test
+    public void givenStringAndLength_whenUsingSplitter_thenTruncate() {
+
+        assertEquals(TruncateString.usingSplitter(TEXT, 3), "Wel");
+    }
+
+}