From 3afadfa5ad95559f4f97f524282459eaef55d33f Mon Sep 17 00:00:00 2001
From: cdjole <djordje.cvijetic@gmail.com>
Date: Tue, 25 Jun 2019 22:05:16 +0200
Subject: [PATCH] BAEL-2994 - String consists of substrings example (#7190)

---
 .../repetition/SubstringRepetition.java       | 29 ++++++++++++
 .../SubstringRepetitionUnitTest.java          | 45 +++++++++++++++++++
 2 files changed, 74 insertions(+)
 create mode 100644 java-strings-2/src/main/java/com/baeldung/string/repetition/SubstringRepetition.java
 create mode 100644 java-strings-2/src/test/java/com/baeldung/string/repetition/SubstringRepetitionUnitTest.java

diff --git a/java-strings-2/src/main/java/com/baeldung/string/repetition/SubstringRepetition.java b/java-strings-2/src/main/java/com/baeldung/string/repetition/SubstringRepetition.java
new file mode 100644
index 000000000000..466ce9146bc0
--- /dev/null
+++ b/java-strings-2/src/main/java/com/baeldung/string/repetition/SubstringRepetition.java
@@ -0,0 +1,29 @@
+package com.baeldung.string.repetition;
+
+public class SubstringRepetition {
+
+    public static boolean containsOnlySubstrings(String string) {
+
+        if (string.length() < 2) {
+            return false;
+        }
+
+        StringBuilder substr = new StringBuilder();
+        for (int i = 0; i < string.length() / 2; i++) {
+            substr.append(string.charAt(i));
+
+            String clearedFromSubstrings = string.replaceAll(substr.toString(), "");
+
+            if (clearedFromSubstrings.length() == 0) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public static boolean containsOnlySubstringsEfficient(String string) {
+
+        return ((string + string).indexOf(string, 1) != string.length());
+    }
+}
diff --git a/java-strings-2/src/test/java/com/baeldung/string/repetition/SubstringRepetitionUnitTest.java b/java-strings-2/src/test/java/com/baeldung/string/repetition/SubstringRepetitionUnitTest.java
new file mode 100644
index 000000000000..fbd948d2bed9
--- /dev/null
+++ b/java-strings-2/src/test/java/com/baeldung/string/repetition/SubstringRepetitionUnitTest.java
@@ -0,0 +1,45 @@
+package com.baeldung.string.repetition;
+
+import static com.baeldung.string.repetition.SubstringRepetition.*;
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class SubstringRepetitionUnitTest {
+
+    private String validString = "aa";
+    private String validStringTwo = "ababab";
+    private String validStringThree = "aabcaabcaabcaabc";
+
+    private String invalidString = "aca";
+    private String invalidStringTwo = "ababa";
+    private String invalidStringThree = "abcdab";
+
+    @Test
+    public void givenValidStrings_whenCheckIfContainsOnlySubstrings_thenReturnsTrue() {
+        assertTrue(containsOnlySubstrings(validString));
+        assertTrue(containsOnlySubstrings(validStringTwo));
+        assertTrue(containsOnlySubstrings(validStringThree));
+    }
+
+    @Test
+    public void givenInvalidStrings_whenCheckIfContainsOnlySubstrings_thenReturnsFalse() {
+        assertFalse(containsOnlySubstrings(invalidString));
+        assertFalse(containsOnlySubstrings(invalidStringTwo));
+        assertFalse(containsOnlySubstrings(invalidStringThree));
+    }
+
+    @Test
+    public void givenValidStrings_whenCheckEfficientlyIfContainsOnlySubstrings_thenReturnsTrue() {
+        assertTrue(containsOnlySubstringsEfficient(validString));
+        assertTrue(containsOnlySubstringsEfficient(validStringTwo));
+        assertTrue(containsOnlySubstringsEfficient(validStringThree));
+    }
+
+    @Test
+    public void givenInvalidStrings_whenCheckEfficientlyIfContainsOnlySubstrings_thenReturnsFalse() {
+        assertFalse(containsOnlySubstringsEfficient(invalidString));
+        assertFalse(containsOnlySubstringsEfficient(invalidStringTwo));
+        assertFalse(containsOnlySubstringsEfficient(invalidStringThree));
+    }
+}