{"id":1415,"date":"2012-07-02T22:20:39","date_gmt":"2012-07-02T20:20:39","guid":{"rendered":"http:\/\/www.tutego.de\/blog\/javainsel\/?p=1415"},"modified":"2012-07-02T22:20:39","modified_gmt":"2012-07-02T20:20:39","slug":"java-8-bekommt-auch-eine-optional-klasse-wie-guava-und-scala","status":"publish","type":"post","link":"https:\/\/www.tutego.de\/blog\/javainsel\/2012\/07\/java-8-bekommt-auch-eine-optional-klasse-wie-guava-und-scala\/","title":{"rendered":"Java 8 bekommt auch eine Optional-Klasse (wie Guava und Scala)"},"content":{"rendered":"
+\/*\n<\/p>
+ * Copyright (c) 2012, Oracle and\/or its affiliates. All rights reserved.\n<\/p>
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.\n<\/p>
+ *\n<\/p>
+ * This code is free software; you can redistribute it and\/or modify it\n<\/p>
+ * under the terms of the GNU General Public License version 2 only, as\n<\/p>
+ * published by the Free Software Foundation.  Oracle designates this\n<\/p>
+ * particular file as subject to the "Classpath" exception as provided\n<\/p>
+ * by Oracle in the LICENSE file that accompanied this code.\n<\/p>
+ *\n<\/p>
+ * This code is distributed in the hope that it will be useful, but WITHOUT\n<\/p>
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or\n<\/p>
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License\n<\/p>
+ * version 2 for more details (a copy is included in the LICENSE file that\n<\/p>
+ * accompanied this code).\n<\/p>
+ *\n<\/p>
+ * You should have received a copy of the GNU General Public License version\n<\/p>
+ * 2 along with this work; if not, write to the Free Software Foundation,\n<\/p>
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.\n<\/p>
+ *\n<\/p>
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA\n<\/p>
+ * or visit www.oracle.com if you need additional information or have any\n<\/p>
+ * questions.\n<\/p>
+ *\/\n<\/p>
+package java.util;\n<\/p>
+\n<\/p>
+import java.util.functions.Factory;\n<\/p>
+import java.util.functions.Mapper;\n<\/p>
+\n<\/p>
+\/**\n<\/p>
+ * Optional\n<\/p>
+ *\n<\/p>
+ * @author Brian Goetz\n<\/p>
+ *\/\n<\/p>
+public class Optional<T> {\n<\/p>
+    private final static Optional<?> EMPTY = new Optional<>();\n<\/p>
+\n<\/p>
+    private final T value;\n<\/p>
+    private final boolean present;\n<\/p>
+\n<\/p>
+    public Optional(T value) {\n<\/p>
+        this.value = value;\n<\/p>
+        this.present = true;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    private Optional() {\n<\/p>
+        this.value = null;\n<\/p>
+        this.present = false;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public static<T> Optional<T> empty() {\n<\/p>
+        return (Optional<T>) EMPTY;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public T get() {\n<\/p>
+        if (!present)\n<\/p>
+            throw new NoSuchElementException();\n<\/p>
+        return value;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public boolean isPresent() {\n<\/p>
+        return present;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public T orElse(T other) {\n<\/p>
+        return present ? value : other;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public T orElse(Factory<T> other) {\n<\/p>
+        return present ? value : other.make();\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public<V extends Throwable> T orElseThrow(Factory<V> exceptionFactory) throws V {\n<\/p>
+        if (present)\n<\/p>
+            return value;\n<\/p>
+        else\n<\/p>
+            throw exceptionFactory.make();\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public<V extends Throwable> T orElseThrow(Class<V> exceptionClass) throws V {\n<\/p>
+        if (present)\n<\/p>
+            return value;\n<\/p>
+        else\n<\/p>
+            try {\n<\/p>
+                throw exceptionClass.newInstance();\n<\/p>
+            }\n<\/p>
+            catch (InstantiationException | IllegalAccessException e) {\n<\/p>
+                throw new IllegalStateException("Unexpected exception: " + e, e);\n<\/p>
+            }\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    public<V> Optional<V> map(Mapper<T, V> mapper) {\n<\/p>
+        return present ? new Optional<>(mapper.map(value)) : Optional.<V>empty();\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    @Override\n<\/p>
+    public boolean equals(Object o) {\n<\/p>
+        if (this == o) return true;\n<\/p>
+        if (o == null || getClass() != o.getClass()) return false;\n<\/p>
+\n<\/p>
+        Optional optional = (Optional) o;\n<\/p>
+\n<\/p>
+        if (present != optional.present) return false;\n<\/p>
+        if (value != null ? !value.equals(optional.value) : optional.value != null) return false;\n<\/p>
+\n<\/p>
+        return true;\n<\/p>
+    }\n<\/p>
+\n<\/p>
+    @Override\n<\/p>
+    public int hashCode() {\n<\/p>
+        int result = value != null ? value.hashCode() : 0;\n<\/p>
+        result = 31 * result + (present ? 1 : 0);\n<\/p>
+        return result;\n<\/p>
+    }\n<\/p>
+}\n<\/p><\/pre>\n

<\/pre>\n","protected":false},"excerpt":{"rendered":"
+\/* + * Copyright (c) 2012, Oracle and\/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and\/or modify it + * under the terms of the GNU General Public License version 2 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[66],"tags":[],"class_list":["post-1415","post","type-post","status-publish","format-standard","hentry","category-java-8"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts\/1415","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/comments?post=1415"}],"version-history":[{"count":1,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts\/1415\/revisions"}],"predecessor-version":[{"id":1416,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/posts\/1415\/revisions\/1416"}],"wp:attachment":[{"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/media?parent=1415"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/categories?post=1415"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tutego.de\/blog\/javainsel\/wp-json\/wp\/v2\/tags?post=1415"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}