Example usage for java.util Map computeIfAbsent

Introduction

In this page you can find the example usage for java.util Map computeIfAbsent.

Prototype

default V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) 

Source Link

Document

If the specified key is not already associated with a value (or is mapped to null ), attempts to compute its value using the given mapping function and enters it into this map unless null .

Usage

From source file:at.gridtec.lambda4j.function.bi.obj.ObjIntFunction.java

/**
 * Returns a memoized (caching) version of this {@link ObjIntFunction}. Whenever it is called, the mapping between
 * the input parameters and the return value is preserved in a cache, making subsequent calls returning the memoized
 * value instead of computing the return value again.
 * <p>/*from   www.ja  v a 2 s  .c  o  m*/
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ObjIntFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ObjIntFunction<T, R> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Pair<T, Integer>, R> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ObjIntFunction<T, R> & Memoized) (t, value) -> {
            final R returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Pair.of(t, value),
                        key -> apply(key.getLeft(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.bi.obj.ObjShortFunction.java

/**
 * Returns a memoized (caching) version of this {@link ObjShortFunction}. Whenever it is called, the mapping between
 * the input parameters and the return value is preserved in a cache, making subsequent calls returning the memoized
 * value instead of computing the return value again.
 * <p>/*from  w w  w  .ja  va 2s .  co m*/
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ObjShortFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ObjShortFunction<T, R> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Pair<T, Short>, R> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ObjShortFunction<T, R> & Memoized) (t, value) -> {
            final R returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Pair.of(t, value),
                        key -> apply(key.getLeft(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.tri.to.ToByteTriFunction.java

/**
 * Returns a memoized (caching) version of this {@link ToByteTriFunction}. Whenever it is called, the mapping
 * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the
 * memoized value instead of computing the return value again.
 * <p>/*w ww  .  j a  va2 s  .c o  m*/
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ToByteTriFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ToByteTriFunction<T, U, V> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Triple<T, U, V>, Byte> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ToByteTriFunction<T, U, V> & Memoized) (t, u, v) -> {
            final byte returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Triple.of(t, u, v),
                        key -> applyAsByte(key.getLeft(), key.getMiddle(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.tri.to.ToLongTriFunction.java

/**
 * Returns a memoized (caching) version of this {@link ToLongTriFunction}. Whenever it is called, the mapping
 * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the
 * memoized value instead of computing the return value again.
 * <p>//from www.  j  a v  a2  s  . c  om
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ToLongTriFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ToLongTriFunction<T, U, V> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Triple<T, U, V>, Long> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ToLongTriFunction<T, U, V> & Memoized) (t, u, v) -> {
            final long returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Triple.of(t, u, v),
                        key -> applyAsLong(key.getLeft(), key.getMiddle(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.bi.obj.ObjCharFunction.java

/**
 * Returns a memoized (caching) version of this {@link ObjCharFunction}. Whenever it is called, the mapping between
 * the input parameters and the return value is preserved in a cache, making subsequent calls returning the memoized
 * value instead of computing the return value again.
 * <p>/*from ww w .ja va 2 s . c om*/
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ObjCharFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ObjCharFunction<T, R> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Pair<T, Character>, R> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ObjCharFunction<T, R> & Memoized) (t, value) -> {
            final R returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Pair.of(t, value),
                        key -> apply(key.getLeft(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.tri.to.ToIntTriFunction.java

/**
 * Returns a memoized (caching) version of this {@link ToIntTriFunction}. Whenever it is called, the mapping between
 * the input parameters and the return value is preserved in a cache, making subsequent calls returning the memoized
 * value instead of computing the return value again.
 * <p>//  ww  w . j  a v  a  2  s.  c  o  m
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ToIntTriFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ToIntTriFunction<T, U, V> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Triple<T, U, V>, Integer> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ToIntTriFunction<T, U, V> & Memoized) (t, u, v) -> {
            final int returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Triple.of(t, u, v),
                        key -> applyAsInt(key.getLeft(), key.getMiddle(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.bi.obj.ObjDoubleFunction.java

/**
 * Returns a memoized (caching) version of this {@link ObjDoubleFunction}. Whenever it is called, the mapping
 * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the
 * memoized value instead of computing the return value again.
 * <p>/*from w ww . jav  a  2s.  c  o  m*/
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ObjDoubleFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ObjDoubleFunction<T, R> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Pair<T, Double>, R> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ObjDoubleFunction<T, R> & Memoized) (t, value) -> {
            final R returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Pair.of(t, value),
                        key -> apply(key.getLeft(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.tri.to.ToFloatTriFunction.java

/**
 * Returns a memoized (caching) version of this {@link ToFloatTriFunction}. Whenever it is called, the mapping
 * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the
 * memoized value instead of computing the return value again.
 * <p>//from   w ww  .j  a  v  a 2 s.  co  m
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ToFloatTriFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ToFloatTriFunction<T, U, V> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Triple<T, U, V>, Float> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ToFloatTriFunction<T, U, V> & Memoized) (t, u, v) -> {
            final float returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Triple.of(t, u, v),
                        key -> applyAsFloat(key.getLeft(), key.getMiddle(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.tri.to.ToShortTriFunction.java

/**
 * Returns a memoized (caching) version of this {@link ToShortTriFunction}. Whenever it is called, the mapping
 * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the
 * memoized value instead of computing the return value again.
 * <p>//w  w  w  . j  a  v a  2  s .  c om
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ToShortTriFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ToShortTriFunction<T, U, V> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Triple<T, U, V>, Short> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ToShortTriFunction<T, U, V> & Memoized) (t, u, v) -> {
            final short returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Triple.of(t, u, v),
                        key -> applyAsShort(key.getLeft(), key.getMiddle(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

From source file:at.gridtec.lambda4j.function.bi.obj.ObjBooleanFunction.java

/**
 * Returns a memoized (caching) version of this {@link ObjBooleanFunction}. Whenever it is called, the mapping
 * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the
 * memoized value instead of computing the return value again.
 * <p>//ww w  .  j a v  a  2  s.c  o m
 * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values
 * forever.
 *
 * @return A memoized (caching) version of this {@code ObjBooleanFunction}.
 * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the
 * resulting memoized function, as the cache used internally does not permit {@code null} keys or values.
 * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it
 * thread-safe.
 */
@Nonnull
default ObjBooleanFunction<T, R> memoized() {
    if (isMemoized()) {
        return this;
    } else {
        final Map<Pair<T, Boolean>, R> cache = new ConcurrentHashMap<>();
        final Object lock = new Object();
        return (ObjBooleanFunction<T, R> & Memoized) (t, value) -> {
            final R returnValue;
            synchronized (lock) {
                returnValue = cache.computeIfAbsent(Pair.of(t, value),
                        key -> apply(key.getLeft(), key.getRight()));
            }
            return returnValue;
        };
    }
}

---

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