Utility for handling checked exceptions in lambdas

winterbe · winterbe · commit 48333293a349 · 2015-03-20T08:58:28.000+01:00
diff --git a/src/com/winterbe/java8/samples/misc/CheckedFunctions.java b/src/com/winterbe/java8/samples/misc/CheckedFunctions.java
@@ -0,0 +1,92 @@
+package com.winterbe.java8.samples.misc;
+
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+/**
+ * Utilities for hassle-free usage of lambda expressions who throw checked exceptions.
+ *
+ * @author Benjamin Winterberg
+ */
+public final class CheckedFunctions {
+
+    @FunctionalInterface
+    public interface CheckedConsumer<T> {
+        void accept(T input) throws Exception;
+    }
+
+    @FunctionalInterface
+    public interface CheckedPredicate<T> {
+        boolean test(T input) throws Exception;
+    }
+
+    @FunctionalInterface
+    public interface CheckedFunction<F, T> {
+        T apply(F input) throws Exception;
+    }
+
+    /**
+     * Return a function which rethrows possible checked exceptions as runtime exception.
+     *
+     * @param function
+     * @param <F>
+     * @param <T>
+     * @return
+     */
+    public static <F, T> Function<F, T> function(CheckedFunction<F, T> function) {
+        return input -> {
+            try {
+                return function.apply(input);
+            }
+            catch (Exception e) {
+                if (e instanceof RuntimeException) {
+                    throw (RuntimeException) e;
+                }
+                throw new RuntimeException(e);
+            }
+        };
+    }
+
+    /**
+     * Return a predicate which rethrows possible checked exceptions as runtime exception.
+     *
+     * @param predicate
+     * @param <T>
+     * @return
+     */
+    public static <T> Predicate<T> predicate(CheckedPredicate<T> predicate) {
+        return input -> {
+            try {
+                return predicate.test(input);
+            }
+            catch (Exception e) {
+                if (e instanceof RuntimeException) {
+                    throw (RuntimeException) e;
+                }
+                throw new RuntimeException(e);
+            }
+        };
+    }
+
+    /**
+     * Return a consumer which rethrows possible checked exceptions as runtime exception.
+     *
+     * @param consumer
+     * @param <T>
+     * @return
+     */
+    public static <T> Consumer<T> consumer(CheckedConsumer<T> consumer) {
+        return input -> {
+            try {
+                consumer.accept(input);
+            }
+            catch (Exception e) {
+                if (e instanceof RuntimeException) {
+                    throw (RuntimeException) e;
+                }
+                throw new RuntimeException(e);
+            }
+        };
+    }
+}
