61 lines
1.5 KiB
Java
61 lines
1.5 KiB
Java
package fr.pandacube.lib.util;
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import java.util.Objects;
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import fr.pandacube.lib.util.ThrowableUtil.SupplierException;
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/**
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* Represents a lazy loaded value.
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*
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* The value will be computed using the Supplier provided in the
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* constructor, only the first time the {@link #get()} method is
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* called.
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*
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* @param <T> the type of the enclosed value.
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*/
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public class LazyOrException<T> implements SupplierException<T> {
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private T cachedValue;
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private final SupplierException<T> supplier;
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private boolean cached = false;
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/**
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* Create a lazy value loader that will call the provided supplier to get the value.
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* @param s the supplier from which the value is fetched.
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*/
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public LazyOrException(SupplierException<T> s) {
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supplier = Objects.requireNonNull(s);
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}
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/**
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* Get the wrapped value, from cache or from the provider if it is not yet cached.
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*
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* If the provider throws an exception, it will be redirected to the caller as is, and no value will be cached
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* (the next call to this method will execute the supplier again).
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*/
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@Override
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public synchronized T get() throws Exception {
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if (!cached)
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set(supplier.get());
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return cachedValue;
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}
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/**
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* Reset the cached value. The next call to {@link #get()} will get the value from the provider.
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*/
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public synchronized void reset() {
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cached = false;
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cachedValue = null;
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}
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/**
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* Manually set the value to the provided one.
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* @param value the value to put in the cache.
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*/
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public synchronized void set(T value) {
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cachedValue = value;
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cached = true;
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}
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}
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