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Lucene example source code file (Constants.java)

This example Lucene source code file (Constants.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

constants, java_1_2, jre_is_64bit, jre_is_64bit, linux, lucene_main_version, lucene_main_version, lucene_version, lucene_version, os_arch, snapshot, string, string, windows

The Lucene Constants.java source code

package org.apache.lucene.util;

 * 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

import org.apache.lucene.LucenePackage;

 * Some useful constants.

public final class Constants {
  private Constants() {}			  // can't construct

  /** The value of <tt>System.getProperty("java.version"). **/
  public static final String JAVA_VERSION = System.getProperty("java.version");
  /** True iff this is Java version 1.1. */
  public static final boolean JAVA_1_1 = JAVA_VERSION.startsWith("1.1.");
  /** True iff this is Java version 1.2. */
  public static final boolean JAVA_1_2 = JAVA_VERSION.startsWith("1.2.");
  /** True iff this is Java version 1.3. */
  public static final boolean JAVA_1_3 = JAVA_VERSION.startsWith("1.3.");
  /** The value of <tt>System.getProperty("os.name"). **/
  public static final String OS_NAME = System.getProperty("os.name");
  /** True iff running on Linux. */
  public static final boolean LINUX = OS_NAME.startsWith("Linux");
  /** True iff running on Windows. */
  public static final boolean WINDOWS = OS_NAME.startsWith("Windows");
  /** True iff running on SunOS. */
  public static final boolean SUN_OS = OS_NAME.startsWith("SunOS");
  /** True iff running on Mac OS X */
  public static final boolean MAC_OS_X = OS_NAME.startsWith("Mac OS X");

  public static final String OS_ARCH = System.getProperty("os.arch");
  public static final String OS_VERSION = System.getProperty("os.version");
  public static final String JAVA_VENDOR = System.getProperty("java.vendor");

  // NOTE: this logic may not be correct; if you know of a
  // more reliable approach please raise it on java-dev!
  public static final boolean JRE_IS_64BIT;
  static {
    String x = System.getProperty("sun.arch.data.model");
    if (x != null) {
      JRE_IS_64BIT = x.indexOf("64") != -1;
    } else {
      if (OS_ARCH != null && OS_ARCH.indexOf("64") != -1) {
        JRE_IS_64BIT = true;
      } else {
        JRE_IS_64BIT = false;

  // this method prevents inlining the final version constant in compiled classes,
  // see: http://www.javaworld.com/community/node/3400
  private static String ident(final String s) {
    return s.toString();
  // NOTE: we track per-segment version as a String with the "X.Y" format, e.g.
  // "4.0", "3.1", "3.0". Therefore when we change this constant, we should keep
  // the format.
  public static final String LUCENE_MAIN_VERSION = ident("3.3");

  public static final String LUCENE_VERSION;
  static {
    Package pkg = LucenePackage.get();
    String v = (pkg == null) ? null : pkg.getImplementationVersion();
    if (v == null) {
    } else if (!v.startsWith(LUCENE_MAIN_VERSION)) {
    LUCENE_VERSION = ident(v);

Other Lucene examples (source code examples)

Here is a short list of links related to this Lucene Constants.java source code file:

my book on functional programming


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