本文整理了Java中io.vavr.control.Either.isLeft()方法的一些代码示例，展示了Either.isLeft()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Either.isLeft()方法的具体详情如下：
包路径：io.vavr.control.Either
类名称：Either
方法名：isLeft

Either.isLeft介绍

[英]Returns whether this Either is a Left.
[中]返回这两者是否为左。

代码示例

代码示例来源：origin: vavr-io/vavr

@Override
default boolean isEmpty() {
  return isLeft();
}

代码示例来源：origin: vavr-io/vavr

@Override
public boolean isEmpty() {
  return either.isLeft();
}

代码示例来源：origin: vavr-io/vavr

@SuppressWarnings("unchecked")
public LeftProjection<L, R> orElse(LeftProjection<? extends L, ? extends R> other) {
  Objects.requireNonNull(other, "other is null");
  return either.isLeft() ? this : (LeftProjection<L, R>) other;
}

代码示例来源：origin: vavr-io/vavr

@SuppressWarnings("unchecked")
public LeftProjection<L, R> orElse(Supplier<? extends LeftProjection<? extends L, ? extends R>> supplier) {
  Objects.requireNonNull(supplier, "supplier is null");
  return either.isLeft() ? this : (LeftProjection<L, R>) supplier.get();
}

代码示例来源：origin: vavr-io/vavr

/**
 * Runs an action in the case this is a projection on a Left value.
 *
 * @param action an action which consumes a Left value
 */
default void orElseRun(Consumer<? super L> action) {
  Objects.requireNonNull(action, "action is null");
  if (isLeft()) {
    action.accept(getLeft());
  }
}

代码示例来源：origin: vavr-io/vavr

default Either<L, R> peekLeft(Consumer<? super L> action) {
  Objects.requireNonNull(action, "action is null");
  if (isLeft()) {
    action.accept(getLeft());
  }
  return this;
}

代码示例来源：origin: vavr-io/vavr

/**
 * Gets the Left value or an alternate value, if the projected Either is a Right.
 *
 * @param other an alternative value
 * @return the left value, if the underlying Either is a Left or else {@code other}
 * @throws NoSuchElementException if the underlying either of this LeftProjection is a Right
 */
@Override
public L getOrElse(L other) {
  return either.isLeft() ? either.getLeft() : other;
}

代码示例来源：origin: vavr-io/vavr

/**
 * Applies the given action to the value if the projected either is a Left. Otherwise nothing happens.
 *
 * @param action An action which takes a left value
 * @return this LeftProjection
 */
@Override
public LeftProjection<L, R> peek(Consumer<? super L> action) {
  Objects.requireNonNull(action, "action is null");
  if (either.isLeft()) {
    action.accept(either.getLeft());
  }
  return this;
}

代码示例来源：origin: vavr-io/vavr

/**
 * Gets the {@code Left} value or throws.
 *
 * @return the left value, if the underlying {@code Either} is a {@code Left}
 * @throws NoSuchElementException if the underlying {@code Either} of this {@code LeftProjection} is a {@code Right}
 */
@Override
public L get() {
  if (either.isLeft()) {
    return either.getLeft();
  } else {
    throw new NoSuchElementException("LeftProjection.get() on Right");
  }
}

代码示例来源：origin: vavr-io/vavr

/**
 * FlatMaps this LeftProjection.
 *
 * @param mapper A mapper
 * @param <U>    Component type of the mapped left value
 * @return this as {@code LeftProjection<L, U>} if a Right is underlying, otherwise a the mapping result of the left value.
 * @throws NullPointerException if {@code mapper} is null
 */
@SuppressWarnings("unchecked")
public <U> LeftProjection<U, R> flatMap(Function<? super L, ? extends LeftProjection<? extends U, R>> mapper) {
  Objects.requireNonNull(mapper, "mapper is null");
  if (either.isLeft()) {
    return (LeftProjection<U, R>) mapper.apply(either.getLeft());
  } else {
    return (LeftProjection<U, R>) this;
  }
}

代码示例来源：origin: vavr-io/vavr

/**
 * Gets the Left value or an alternate value, if the projected Either is a Right.
 *
 * @param other a function which converts a Right value to an alternative Left value
 * @return the left value, if the underlying Either is a Left or else the alternative Left value provided by
 * {@code other} by applying the Right value.
 */
public L getOrElseGet(Function<? super R, ? extends L> other) {
  Objects.requireNonNull(other, "other is null");
  if (either.isLeft()) {
    return either.getLeft();
  } else {
    return other.apply(either.get());
  }
}

代码示例来源：origin: vavr-io/vavr

/**
 * Gets the Left value or throws, if the projected Either is a Right.
 *
 * @param <X>               a throwable type
 * @param exceptionFunction a function which creates an exception based on a Right value
 * @return the left value, if the underlying Either is a Left or else throws the exception provided by
 * {@code exceptionFunction} by applying the Right value.
 * @throws X if the projected Either is a Right
 */
public <X extends Throwable> L getOrElseThrow(Function<? super R, X> exceptionFunction) throws X {
  Objects.requireNonNull(exceptionFunction, "exceptionFunction is null");
  if (either.isLeft()) {
    return either.getLeft();
  } else {
    throw exceptionFunction.apply(either.get());
  }
}

代码示例来源：origin: vavr-io/vavr

/**
 * Filters this right-biased {@code Either} by testing a predicate.
 * <p>
 *
 * @param predicate A predicate
 * @return a new {@code Option} instance
 * @throws NullPointerException if {@code predicate} is null
 */
default Option<Either<L, R>> filter(Predicate<? super R> predicate) {
  Objects.requireNonNull(predicate, "predicate is null");
  return isLeft() || predicate.test(get()) ? Option.some(this) : Option.none();
}

代码示例来源：origin: vavr-io/vavr

/**
 * Maps the left value if the projected Either is a Left.
 *
 * @param mapper A mapper which takes a left value and returns a value of type U
 * @param <U>    The new type of a Left value
 * @return A new LeftProjection
 */
@SuppressWarnings("unchecked")
@Override
public <U> LeftProjection<U, R> map(Function<? super L, ? extends U> mapper) {
  Objects.requireNonNull(mapper, "mapper is null");
  if (either.isLeft()) {
    return either.mapLeft((Function<L, U>) mapper).left();
  } else {
    return (LeftProjection<U, R>) this;
  }
}

代码示例来源：origin: vavr-io/vavr

/**
 * Returns {@code Some} value of type R if this is a right projection of a Right value and the predicate
 * applies to the underlying value.
 *
 * @param predicate A predicate
 * @return A new Option
 */
public Option<RightProjection<L, R>> filter(Predicate<? super R> predicate) {
  Objects.requireNonNull(predicate, "predicate is null");
  return either.isLeft() || predicate.test(either.get()) ? Option.some(this) : Option.none();
}

代码示例来源：origin: vavr-io/vavr

/**
 * Maps the value of this Either if it is a Left, performs no operation if this is a Right.
 *
 * <pre>{@code
 * import static io.vavr.API.*;
 *
 * // = Left(2)
 * Left(1).mapLeft(i -> i + 1);
 *
 * // = Right("a")
 * Right("a").mapLeft(i -> i + 1);
 * }</pre>
 *
 * @param leftMapper A mapper
 * @param <U>        Component type of the mapped right value
 * @return a mapped {@code Monad}
 * @throws NullPointerException if {@code mapper} is null
 */
@SuppressWarnings("unchecked")
default <U> Either<U, R> mapLeft(Function<? super L, ? extends U> leftMapper) {
  Objects.requireNonNull(leftMapper, "leftMapper is null");
  if (isLeft()) {
    return Either.left(leftMapper.apply(getLeft()));
  } else {
    return (Either<U, R>) this;
  }
}

代码示例来源：origin: vavr-io/vavr

/**
 * Filters this right-biased {@code Either} by testing a predicate.
 * If the {@code Either} is a {@code Right} and the predicate doesn't match, the
 * {@code Either} will be turned into a {@code Left} with contents computed by applying
 * the filterVal function to the {@code Either} value.
 *
 * <pre>{@code
 * import static io.vavr.API.*;
 *
 * // = Left("bad: a")
 * Right("a").filterOrElse(i -> false, val -> "bad: " + val);
 *
 * // = Right("a")
 * Right("a").filterOrElse(i -> true, val -> "bad: " + val);
 * }</pre>
 *
 * @param predicate A predicate
 * @param zero      A function that turns a right value into a left value if the right value does not make it through the filter.
 * @return an {@code Either} instance
 * @throws NullPointerException if {@code predicate} is null
 */
default Either<L,R> filterOrElse(Predicate<? super R> predicate, Function<? super R, ? extends L> zero) {
  Objects.requireNonNull(predicate, "predicate is null");
  Objects.requireNonNull(zero, "zero is null");
  if (isLeft() || predicate.test(get())) {
    return this;
  } else {
    return Either.left(zero.apply(get()));
  }
}

代码示例来源：origin: vavr-io/vavr

@Override
public Iterator<L> iterator() {
  if (either.isLeft()) {
    return Iterator.of(either.getLeft());
  } else {
    return Iterator.empty();
  }
}

代码示例来源：origin: io.vavr/vavr

/**
 * Gets the Left value or an alternate value, if the projected Either is a Right.
 *
 * @param other an alternative value
 * @return the left value, if the underlying Either is a Left or else {@code other}
 * @throws NoSuchElementException if the underlying either of this LeftProjection is a Right
 */
@Override
public L getOrElse(L other) {
  return either.isLeft() ? either.getLeft() : other;
}

代码示例来源：origin: io.vavr/vavr

/**
 * Filters this right-biased {@code Either} by testing a predicate.
 * <p>
 *
 * @param predicate A predicate
 * @return a new {@code Option} instance
 * @throws NullPointerException if {@code predicate} is null
 */
default Option<Either<L, R>> filter(Predicate<? super R> predicate) {
  Objects.requireNonNull(predicate, "predicate is null");
  return isLeft() || predicate.test(get()) ? Option.some(this) : Option.none();
}