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

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

@@ -0,0 +1,60 @@
+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 Panagram {
+
+    public static boolean isPanagram(String str) {
+        if (str == null)
+            return false;
+        Boolean[] alphabetMarker = new Boolean[26];
+        Arrays.fill(alphabetMarker, false);
+        int alphabetIndex = 0;
+        str = str.toUpperCase();
+        for (int i = 0; i < str.length(); i++) {
+            if ('A' <= str.charAt(i) && str.charAt(i) <= 'Z') {
+                alphabetIndex = str.charAt(i) - 'A';
+                alphabetMarker[alphabetIndex] = true;
+            }
+        }
+        for (boolean index : alphabetMarker) {
+            if (!index)
+                return false;
+        }
+        return true;
+    }
+
+    public static boolean isPanagramWithStreams(String str) {
+        if (str == null)
+            return false;
+        
+        // filtered character stream
+        str = str.toUpperCase();
+        Stream<Character> filteredCharStream = str.chars()
+            .filter(item -> ((item >= 'A' && item <= 'Z') || (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() == 26);
+    }
+
+    public static boolean isPerfectPanagram(String str) {
+        if (str == null)
+            return false;
+        
+        // filtered character stream
+        str = str.toUpperCase();
+        Stream<Character> filteredCharStream = str.chars()
+            .filter(item -> ((item >= 'A' && item <= 'Z') || (item >= 'a' && item <= 'z')))
+            .mapToObj(c -> (char) c);
+        Map<Character, Long> alphabetFrequencyMap = filteredCharStream.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
+
+        return (alphabetFrequencyMap.size() == 26 && alphabetFrequencyMap.values()
+            .stream()
+            .allMatch(item -> item == 1));
+    }
+}