In this post, we will write a Java program to check if the String contains only Unicode letters.
Program explanation:
- This program uses Character.isLetter(cs.charAt(i) method to check if the character is letter or not.
- testIsAlpha() JUnit test case for testing this program.
How to Check if the String Contains only Letters
Let's write a Java method to check if the given String contains only letters or not:
public static boolean isAlpha(final CharSequence cs) { if (isEmpty(cs)) { return false; } final int sz = cs.length(); for (int i = 0; i < sz; i++) { if (!Character.isLetter(cs.charAt(i))) { return false; } } return true; } public static boolean isEmpty(final CharSequence cs) { return cs == null || cs.length() == 0; }
Let's write a complete Java program with JUnit test cases to test the above method:
import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; import org.junit.Test; /** * Checks if the CharSequence contains only Unicode letters * @author javaguides.net * */ public class IsAlphaExample { public static boolean isAlpha(final CharSequence cs) { if (isEmpty(cs)) { return false; } final int sz = cs.length(); for (int i = 0; i < sz; i++) { if (!Character.isLetter(cs.charAt(i))) { return false; } } return true; } public static boolean isEmpty(final CharSequence cs) { return cs == null || cs.length() == 0; } @Test public void testIsAlpha() { assertFalse(isAlpha(null)); assertFalse(isAlpha("")); assertFalse(isAlpha(" ")); assertTrue(isAlpha("a")); assertTrue(isAlpha("A")); assertTrue(isAlpha("kgKgKgKgkgkGkjkjlJlOKLgHdGdHgl")); assertFalse(isAlpha("ham kso")); assertFalse(isAlpha("1")); assertFalse(isAlpha("hkHKHik6iUGHKJgU7tUJgKJGI87GIkug")); assertFalse(isAlpha("_")); assertFalse(isAlpha("hkHKHik*khbkuh")); } }
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