1 2 package org.hamcrest.text; 3 4 import org.hamcrest.Description; 5 import org.hamcrest.Matcher; 6 import org.hamcrest.TypeSafeMatcher; 7 8 import java.util.regex.Pattern; 9 10 import static org.hamcrest.core.AnyOf.anyOf; 11 import static org.hamcrest.core.IsNull.nullValue; 12 13 /** 14 * Matches blank Strings (and null). 15 */ 16 public final class IsBlankString extends TypeSafeMatcher<String> { 17 private static final IsBlankString BLANK_INSTANCE = new IsBlankString(); 18 @SuppressWarnings("unchecked") 19 private static final Matcher<String> NULL_OR_BLANK_INSTANCE = anyOf(nullValue(), BLANK_INSTANCE); 20 21 private static final Pattern REGEX_WHITESPACE = Pattern.compile("\\s*"); 22 23 private IsBlankString() { } 24 25 @Override 26 public boolean matchesSafely(String item) { 27 return REGEX_WHITESPACE.matcher(item).matches(); 28 } 29 30 @Override 31 public void describeTo(Description description) { 32 description.appendText("a blank string"); 33 } 34 35 /** 36 * Creates a matcher of {@link String} that matches when the examined string contains 37 * zero or more whitespace characters and nothing else. 38 * For example: 39 * <pre>assertThat(" ", is(blankString()))</pre> 40 */ 41 public static Matcher<String> blankString() { 42 return BLANK_INSTANCE; 43 } 44 45 /** 46 * Creates a matcher of {@link String} that matches when the examined string is <code>null</code>, or 47 * contains zero or more whitespace characters and nothing else. 48 * For example: 49 * <pre>assertThat(((String)null), is(blankOrNullString()))</pre> 50 * 51 */ 52 public static Matcher<String> blankOrNullString() { 53 return NULL_OR_BLANK_INSTANCE; 54 } 55 } 56
