---
title: 'Java 8 bekommt auch eine Optional-Klasse (wie Guava und Scala)'
url: 'https://www.tutego.de/blog/javainsel/2012/07/java-8-bekommt-auch-eine-optional-klasse-wie-guava-und-scala'
markdown: 'https://www.tutego.de/blog/javainsel/2012/07/java-8-bekommt-auch-eine-optional-klasse-wie-guava-und-scala.md'
date: '2012-07-02'
description: '+/* + * 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 only, as + * …'
taxonomy:
  category:
    - 'Java 8'
---

# Java 8 bekommt auch eine Optional-Klasse (wie Guava und Scala)

![Illustration einer tropischen Insel mit Palmen und einem hohen Berg](https://www.tutego.de/blog/javainsel/user/themes/tutego/images/insel-cover.jpg)# Java Blog für Programmierer

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## Java 8 bekommt auch eine Optional-Klasse (wie Guava und Scala)

02.07.2012 · [Christian Ullenboom](https://www.tutego.de/blog/javainsel/author/admin/)

 ```diff
+/*
+ * 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 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.util;
+
+import java.util.functions.Factory;
+import java.util.functions.Mapper;
+
+/**
+ * Optional
+ *
+ * @author Brian Goetz
+ */
+public class Optional {
+    private final static Optional EMPTY = new Optional();
+
+    private final T value;
+    private final boolean present;
+
+    public Optional(T value) {
+        this.value = value;
+        this.present = true;
+    }
+
+    private Optional() {
+        this.value = null;
+        this.present = false;
+    }
+
+    public static Optional empty() {
+        return (Optional) EMPTY;
+    }
+
+    public T get() {
+        if (!present)
+            throw new NoSuchElementException();
+        return value;
+    }
+
+    public boolean isPresent() {
+        return present;
+    }
+
+    public T orElse(T other) {
+        return present ? value : other;
+    }
+
+    public T orElse(Factory other) {
+        return present ? value : other.make();
+    }
+
+    public T orElseThrow(Factory exceptionFactory) throws V {
+        if (present)
+            return value;
+        else
+            throw exceptionFactory.make();
+    }
+
+    public T orElseThrow(Class exceptionClass) throws V {
+        if (present)
+            return value;
+        else
+            try {
+                throw exceptionClass.newInstance();
+            }
+            catch (InstantiationException | IllegalAccessException e) {
+                throw new IllegalStateException("Unexpected exception: " + e, e);
+            }
+    }
+
+    public Optional map(Mapper mapper) {
+        return present ? new Optional(mapper.map(value)) : Optional.empty();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Optional optional = (Optional) o;
+
+        if (present != optional.present) return false;
+        if (value != null ? !value.equals(optional.value) : optional.value != null) return false;
+
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = value != null ? value.hashCode() : 0;
+        result = 31 * result + (present ? 1 : 0);
+        return result;
+    }
+}

```

```text

```

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