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Apache Isis Commons is a library with utilities, that are shared with the entire Apache Isis ecosystem.

There is a newer version: 2.0.0-M9

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */

package org.apache.isis.commons.internal;

import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.Writer;
import java.lang.annotation.Annotation;

import org.springframework.context.annotation.Primary;

/**
 * - internal use only -
 * 
 * A collection of commonly used constants.
 * 
 * 
 * WARNING: Do NOT use any of the classes provided by this package! 

 * These may be changed or removed without notice!
 * 
 *
 * @since 2.0
 */
public final class _Constants {

    private _Constants(){}

    /**
     * Convenient e.g. for reflective invocation
     */
    public static final Object[] emptyObjects = new Object[0];

    /**
     * Convenient e.g. for reflective invocation
     */
    public static final Class[] emptyClasses = new Class[0];

    /**
     * Convenient e.g. for reflective invocation
     */
    public static final Class[] classesOfObject = new Class[] { Object.class };

    /**
     * Convenient e.g. for toArray conversions
     */
    public static final String[] emptyStringArray = new String[0];

    /**
     * empty array of byte
     */
    public static final byte[] emptyBytes = new byte[0];

    /**
     * empty array of Annotation
     */
    public static final Annotation[] emptyAnnotations = new Annotation[0];

    /**
     * Writer that does nothing
     */
    public static final Writer nopWriter = new Writer() {
        @Override public void write(final char[] cbuf, final int off, final int len) throws IOException { }
        @Override public void flush() throws IOException { }
        @Override public void close() throws IOException { }
    };

    /**
     * OutputStream that does nothing
     */
    public static final OutputStream nopOutputStream = new OutputStream() {
        @Override public void write(final int b) throws IOException { }
    };

    /**
     * PrintStream that does nothing
     */
    public static final PrintStream nopPrintStream = new PrintStream(nopOutputStream);

    @Primary private static final class PrimaryAnnotated {}
    public static final Primary ANNOTATION_PRIMARY = PrimaryAnnotated.class.getAnnotation(Primary.class);

}