Da null viel zu oft vorkommt, null-Referenzierungen aber vermieden werden müssen, gibt es viel Code der Art: o != null ? o : non_null_o.

Diverse Programmiersprachen bieten für dieses Konstrukt eine Abkürzung über den sogenannten null coalescing operator (Coalescing, zu Deutsch verschmelzend), der geschrieben wird mal als ?? oder als ?:, für unser Beispiel: o ?? non_null_o. Besonders hübsch ist dass bei sequenziellen Tests der Art o ?? p ?? q ?? r, wo es dann sinngemäß lautete: Liefere die erste Referenz ungleich null.

Java-Programmierer kommen nicht zu diesem Glück, können aber tricksen (http://stackoverflow.com/a/28306286/388317):

If there are only two references to test and you are using Java 8, you could use

Object o = null;
Object p = "p";
Object r = Optional.ofNullable( o ).orElse( p );
System.out.println( r );   // p

If you import static Optional the expression is not too bad.

Unfortunately your case with „several variables“ is not possible with an Optional-method. Instead you could use:

Object o = null;
Object p = null;
Object q = "p";

Optional<Object> r = Stream.of( o, p, q ).filter( Objects::nonNull ).findFirst();
System.out.println( r.get() );   // p

Es ist angeraten die Updates zu installieren:

• Java SE 8u31: http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
• Java SE 7u75/76:  http://www.oracle.com/technetwork/java/javase/downloads/index-jsp-138363.html#JDK7

Oracle stuft die Fehler als kritisch ein.

http://www.oracle.com/technetwork/topics/security/cpujan2015-1972971.html

http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/003295073abf zeigt uns in Java 9 endlich eine lang erwartete Methode:

+    /**
+     * Reads all bytes from this input stream and writes the bytes to the
+     * given output stream in the order that they are read. On return, this
+     * input stream will be at end of stream. This method does not close either
+     * stream.
+     * <p>
+     * This method may block indefinitely reading from the input stream, or
+     * writing to the output stream. The behavior for the case where the input
+     * and/or output stream is <i>asynchronously closed</i>, or the thread
+     * interrupted during the transfer, is highly input and output stream
+     * specific, and therefore not specified.
+     * <p>
+     * If an I/O error occurs reading from the input stream or writing to the
+     * output stream, then it may do so after some bytes have been read or
+     * written. Consequently the input stream may not be at end of stream and
+     * one, or both, streams may be in an inconsistent state. It is strongly
+     * recommended that both streams be promptly closed if an I/O error occurs.
+     *
+     * @param  out the output stream, non-null
+     * @return the number of bytes transferred
+     * @throws IOException if an I/O error occurs when reading or writing
+     * @throws NullPointerException if {@code out} is {@code null}
+     *
+     * @since 1.9
+     */
+    public long transferTo(OutputStream out) throws IOException {
+        Objects.requireNonNull(out, "out");
+        long transferred = 0;
+        byte[] buffer = new byte[TRANSFER_BUFFER_SIZE];
+        int read;
+        while ((read = this.read(buffer, 0, TRANSFER_BUFFER_SIZE)) >= 0) {
+            out.write(buffer, 0, read);
+            transferred += read;
+        }
+        return transferred;
+    }