Merge pull request eugenp#6052 from jainvarz/BAEL-2536-check-for-a-panagram-string

BAEL-2536-check-for-a-panagram-string

Author: eric-martin

java-strings/src/main/java/com/baeldung/string/Pangram.java

@@ -0,0 +1,61 @@
+package com.baeldung.string;
+
+import java.util.Arrays;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class Pangram {
+    private static final int ALPHABET_COUNT = 26;
+
+    public static boolean isPangram(String str) {
+        if (str == null)
+            return false;
+        Boolean[] alphabetMarker = new Boolean[ALPHABET_COUNT];
+        Arrays.fill(alphabetMarker, false);
+        int alphabetIndex = 0;
+        String strUpper = str.toUpperCase();
+        for (int i = 0; i < str.length(); i++) {
+            if ('A' <= strUpper.charAt(i) && strUpper.charAt(i) <= 'Z') {
+                alphabetIndex = strUpper.charAt(i) - 'A';
+                alphabetMarker[alphabetIndex] = true;
+            }
+        }
+        for (boolean index : alphabetMarker) {
+            if (!index)
+                return false;
+        }
+        return true;
+    }
+
+    public static boolean isPangramWithStreams(String str) {
+        if (str == null)
+            return false;
+
+        // filtered character stream
+        String strUpper = str.toUpperCase();
+        Stream<Character> filteredCharStream = strUpper.chars()
+            .filter(item -> ((item >= 'A' && item <= 'Z')))
+            .mapToObj(c -> (char) c);
+        Map<Character, Boolean> alphabetMap = filteredCharStream.collect(Collectors.toMap(item -> item, k -> Boolean.TRUE, (p1, p2) -> p1));
+
+        return (alphabetMap.size() == ALPHABET_COUNT);
+    }
+
+    public static boolean isPerfectPangram(String str) {
+        if (str == null)
+            return false;
+
+        // filtered character stream
+        String strUpper = str.toUpperCase();
+        Stream<Character> filteredCharStream = strUpper.chars()
+            .filter(item -> ((item >= 'A' && item <= 'Z')))
+            .mapToObj(c -> (char) c);
+        Map<Character, Long> alphabetFrequencyMap = filteredCharStream.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
+
+        return (alphabetFrequencyMap.size() == ALPHABET_COUNT && alphabetFrequencyMap.values()
+            .stream()
+            .allMatch(item -> item == 1));
+    }
+}

java-strings/src/test/java/com/baeldung/string/PangramUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.string;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import org.junit.Test;
+
+public class PangramUnitTest {
+
+    @Test
+    public void givenValidString_isPangram_shouldReturnSuccess() {
+        String input = "Two driven jocks help fax my big quiz";
+        assertTrue(Pangram.isPangram(input));
+        assertTrue(Pangram.isPangramWithStreams(input));
+    }
+
+    @Test
+    public void givenNullString_isPangram_shouldReturnFailure() {
+        String input = null;
+        assertFalse(Pangram.isPangram(input));
+        assertFalse(Pangram.isPangramWithStreams(input));
+        assertFalse(Pangram.isPerfectPangram(input));
+    }
+
+    @Test
+    public void givenPerfectPangramString_isPerfectPangram_shouldReturnSuccess() {
+        String input = "abcdefghijklmNoPqrStuVwxyz";
+        assertTrue(Pangram.isPerfectPangram(input));
+    }
+
+    @Test
+    public void givenNonPangramString_isPangram_shouldReturnFailure() {
+        String input = "invalid pangram";
+        assertFalse(Pangram.isPangram(input));
+        assertFalse(Pangram.isPangramWithStreams(input));
+    }
+
+    @Test
+    public void givenPangram_isPerfectPangram_shouldReturnFailure() {
+        String input = "Two driven jocks help fax my big quiz";
+        assertFalse(Pangram.isPerfectPangram(input));
+    }
+
+}