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Detect Pangram in Java

The challenge

A pangram is a sentence that contains every single letter of the alphabet at least once. For example, the sentence “The quick brown fox jumps over the lazy dog” is a pangram, because it uses the letters A-Z at least once (case is irrelevant).

Given a string, detect whether or not it is a pangram. Return True if it is, False if not. Ignore numbers and punctuation.

The solution in Java code

Option 1 (using a Character loop):

public class PangramChecker { public boolean check(String sentence){ for (char c = 'a'; c<='z'; c++) if (!sentence.toLowerCase().contains("" + c)) return false; return true; } }
Code language: Java (java)

Option 2 (using a functional programming to reduce and count the distinct characters):

class PangramChecker { boolean check(final String sentence) { return sentence.chars() .filter(Character::isLetter) .map(Character::toLowerCase) .distinct() .count() == 26; } }
Code language: Java (java)

Option 3 (using an explicit check on all the characters):

public class PangramChecker { public boolean check(String sentence){ String x = sentence.toLowerCase(); if(x.contains("a") && x.contains("b") && x.contains("c") && x.contains("d") && x.contains("e") && x.contains("f") && x.contains("g") && x.contains("h") && x.contains("i") && x.contains("j") && x.contains("k") && x.contains("l") && x.contains("m") && x.contains("n") && x.contains("o") && x.contains("p") && x.contains("q") && x.contains("r") && x.contains("s") && x.contains("t") && x.contains("u") && x.contains("v") && x.contains("w") && x.contains("x") && x.contains("y") && x.contains("z")){ return true; }else{ return false; } } }
Code language: Java (java)

Test cases to validate our solution

import org.junit.Test; import static org.junit.Assert.assertEquals; import org.junit.runners.JUnit4; public class PangramTest { @Test public void test1() { String pangram1 = "The quick brown fox jumps over the lazy dog."; PangramChecker pc = new PangramChecker(); assertEquals(true, pc.check(pangram1)); } @Test public void test2() { String pangram2 = "You shall not pass!"; PangramChecker pc = new PangramChecker(); assertEquals(false, pc.check(pangram2)); } }
Code language: Java (java)

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