Constants.java example

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solrcene-master
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,
 * 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.
 */

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")<tt>. **/
  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")<tt>. **/
  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");

  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();
  }
  
  public static final String LUCENE_MAIN_VERSION = ident("4.0");

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