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Add isNullOrEmpty, isNullOrBlank and isNotNullOrBlank to Strings. #10

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Merged
merged 1 commit into from
Jun 2, 2014
Merged

Add isNullOrEmpty, isNullOrBlank and isNotNullOrBlank to Strings. #10

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48 changes: 48 additions & 0 deletions core/src/main/java/fj/function/Strings.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,10 @@

import fj.F;
import fj.F2;
import fj.data.Stream;
import static fj.Function.curry;
import static fj.function.Booleans.not;
import static fj.function.Characters.isWhitespace;

/**
* Curried string functions.
Expand All @@ -14,8 +17,41 @@ private Strings() {
throw new UnsupportedOperationException();
}

/**
* This function checks if a given String contains any non-whitespace character
* (according to {@link Character#isWhitespace(char)}) and if it's also not
* <code>null</code> and not empty ("").
*
* @see #isNullOrBlank
* @see Character#isWhitespace(char)
* @see Characters#isWhitespace
*/
public static final F<String, Boolean> isNotNullOrBlank = new F<String, Boolean>() {
@Override
public Boolean f(final String a) {
return isNotNullOrEmpty.f(a) && Stream.fromString(a).find(not(isWhitespace)).isSome();
}
};

/**
* This function checks if a given String is whitespace (according to {@link Character#isWhitespace(char)}),
* empty ("") or <code>null</code>.
*
* @see #isNotNullOrBlank
* @see Character#isWhitespace(char)
* @see Characters#isWhitespace
*/
public static final F<String, Boolean> isNullOrBlank = new F<String, Boolean>() {
@Override
public Boolean f(final String a) {
return isNullOrEmpty.f(a) || Stream.fromString(a).find(not(isWhitespace)).isNone();
}
};

/**
* This function checks if a given String is neither <code>null</code> nor empty.
*
* @see #isNullOrEmpty
*/
public static final F<String, Boolean> isNotNullOrEmpty = new F<String, Boolean>() {
@Override
Expand All @@ -24,6 +60,18 @@ public Boolean f(final String a) {
}
};

/**
* This function checks if a given String is <code>null</code> or empty ({@link String#isEmpty()}).
*
* @see #isNotNullOrEmpty
*/
public static final F<String, Boolean> isNullOrEmpty = new F<String, Boolean>() {
@Override
public Boolean f(final String a) {
return a == null || a.length() == 0;
}
};

/**
* A curried version of {@link String#isEmpty()}.
*/
Expand Down