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== Deals with the different version of the Java Virtual Machine. ==



<source lang="java">

/*
* $Id: JVM.java,v 1.3 2009/02/22 02:01:04 kschaefe Exp $
*
* Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
* Santa Clara, California 95054, U.S.A. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
import javax.swing.UIManager;
import javax.swing.UIManager.LookAndFeelInfo;
/**
* Deals with the different version of the Java Virtual Machine. 
*/
public class JVM {
public final static int JDK1_0 = 10;
public final static int JDK1_1 = 11;
public final static int JDK1_2 = 12;
public final static int JDK1_3 = 13;
public final static int JDK1_4 = 14;
public final static int JDK1_5 = 15;
public final static int JDK1_6 = 16;
public final static int JDK1_6N = 1610;
public final static int JDK1_7 = 17;
private static JVM current;
static {
current = new JVM();
}
/**
* @return the current JVM object
*/
public static JVM current() {
return current;
}
private int jdkVersion;
/**
* Creates a new JVM data from the <code>java.version</code>
* System property
*
*/
public JVM() {
this(System.getProperty("java.version"));
}
/**
* Constructor for the OS object
*/
public JVM(String p_JavaVersion) {
if (p_JavaVersion.startsWith("1.7.")) {
jdkVersion = JDK1_7;
} else if (p_JavaVersion.startsWith("1.6.")) {
for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
if ("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel".equals(info.getClassName())) {
jdkVersion = JDK1_6N;
break;
}
}

jdkVersion = jdkVersion == 0 ? JDK1_6 : jdkVersion;
} else if (p_JavaVersion.startsWith("1.5.")) {
jdkVersion = JDK1_5;
} else if (p_JavaVersion.startsWith("1.4.")) {
jdkVersion = JDK1_4;
} else if (p_JavaVersion.startsWith("1.3.")) {
jdkVersion = JDK1_3;
} else if (p_JavaVersion.startsWith("1.2.")) {
jdkVersion = JDK1_2;
} else if (p_JavaVersion.startsWith("1.1.")) {
jdkVersion = JDK1_1;
} else if (p_JavaVersion.startsWith("1.0.")) {
jdkVersion = JDK1_0;
} else {
// unknown version, assume 1.3
jdkVersion = JDK1_3;
}
}
public boolean isOrLater(int p_Version) {
return jdkVersion >= p_Version;
}
public boolean isOneDotOne() {
return jdkVersion == JDK1_1;
}
public boolean isOneDotTwo() {
return jdkVersion == JDK1_2;
}
public boolean isOneDotThree() {
return jdkVersion == JDK1_3;
}
public boolean isOneDotFour() {
return jdkVersion == JDK1_4;
}
public boolean isOneDotFive() {
return jdkVersion == JDK1_5;
}
public boolean isOneDotSix() {
return jdkVersion == JDK1_6;
}
/**
* Determines if the version of JDK1_6 has Nimbus Look and Feel installed.
*
* @return {@code true} if Nimbus is available and the version is 1.6;
* {@code false} otherwise
*/
public boolean isOneDotSixUpdateN() {
return jdkVersion == JDK1_6N;
}

public boolean isOneDotSeven() {
return jdkVersion == JDK1_7;
}
}

</source>



== Determine the JDK Version Number ==



<source lang="java">

/** Determine the JDK Version Number
*
* There is a human readible JDK version number available as a Java property. The property name is called "java.version".
* Unfortunately it is complicated to parse it mechanically. A somewhat better choice is the Java property called
* "java.class.version". The property value can be converted to a floating pointer value. JDK 1.1 implies 45.3. JDK 1.2
* implies 46.0. JDK 1.3 implies 47.0. JDK 1.4 implies 48.0.
* 
* java.class.version property value
* <ul>
* <li> JDK 1.1 = 45.3
* <li> JDK 1.2 = 46.0
* <li> JDK 1.3 = 47.0
* <li> JDK 1.4 = 48.0
* </ul>
*
* @author Thomas Rischbeck <thomas.rischbeck@arjuna.ru>
* @version $Id: VersionCheck.java 2342 2006-03-30 13:06:17Z $
*/
public class VersionCheck {
private static final String CLASS_VERSION = System.getProperty("java.class.version","44.0");
private static final boolean IS_JDK_11 = ("46.0".rupareTo(CLASS_VERSION) > 0) && ("45.3".rupareTo(CLASS_VERSION) <= 0);
private static final boolean IS_JDK_12 = ("47.0".rupareTo(CLASS_VERSION) > 0) && ("46.0".rupareTo(CLASS_VERSION) <= 0);
private static final boolean IS_JDK_13 = ("48.0".rupareTo(CLASS_VERSION) > 0) && ("47.0".rupareTo(CLASS_VERSION) <= 0);
private static final boolean IS_JDK_14 = ("49.0".rupareTo(CLASS_VERSION) > 0) && ("48.0".rupareTo(CLASS_VERSION) <= 0);
private static final boolean IS_JDK_13_OR_BELOW = IS_JDK_11 || IS_JDK_12 || IS_JDK_13;
private static final boolean IS_JDK_14_OR_ABOVE = ("48.0".rupareTo(CLASS_VERSION) <= 0);

public static final boolean isJDK11only()
{
return IS_JDK_11;
}
public static final boolean isJDK12only()
{
return IS_JDK_12;
}
public static final boolean isJDK13only()
{
return IS_JDK_13;
}
public static final boolean isJDK14only()
{
return IS_JDK_14;
}
public static final boolean isJDK13orBelow()
{
return IS_JDK_13_OR_BELOW;
}
public static final boolean isJDK14orAbove()
{
return IS_JDK_14_OR_ABOVE;
}
}

</source>



== Provides common access to specifics about the version of Java that a virtual machine supports. ==



<source lang="java">

/*
* JBoss, Home of Professional Open Source.
* Copyright 2006, Red Hat Middleware LLC, and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/

/**
* Provides common access to specifics about the version of Java
* that a virtual machine supports.
*
* Determines the version of the Java Virtual Machine by checking
* for the availablity of version specific classes.
*
* Classes are loaded in the following order:
* <ol>
* <li><tt>java.lang.Void</tt> was introduced in JDK 1.1</li>
* <li><tt>java.lang.ThreadLocal</tt> was introduced in JDK 1.2</li>
* <li><tt>java.lang.StrictMath</tt> was introduced in JDK 1.3</li>
* <li><tt>java.lang.StackTraceElement</tt> was introduced in JDK 1.4</li>
* <li><tt>java.lang.Enum</tt> was introduced in JDK 1.5</li>
* <li><tt>java.lang.management.LockInfo</tt> was introduced in JDK 1.6</li>
* </ol>
* 
*
* @version <tt>$Revision: 2240 $</tt>
* @author
*/
public final class Java
{
/** Prevent instantiation */
private Java() {}
/** Java version 1.0 token */
public static final int VERSION_1_0 = 0x01;
/** Java version 1.1 token */
public static final int VERSION_1_1 = 0x02;
/** Java version 1.2 token */
public static final int VERSION_1_2 = 0x03;
/** Java version 1.3 token */
public static final int VERSION_1_3 = 0x04;
/** Java version 1.4 token */
public static final int VERSION_1_4 = 0x05;

/** Java version 1.5 token */
public static final int VERSION_1_5 = 0x06;

/** Java version 1.6 token */
public static final int VERSION_1_6 = 0x07;

/**
* Private to avoid over optimization by the compiler.
*
* @see #getVersion() Use this method to access this final value.
*/
private static final int VERSION;
/** Initialize VERSION. */
static
{
// default to 1.0
int version = VERSION_1_0;
try
{
// check for 1.1
Class.forName("java.lang.Void");
version = VERSION_1_1;
// check for 1.2
Class.forName("java.lang.ThreadLocal");
version = VERSION_1_2;
// check for 1.3
Class.forName("java.lang.StrictMath");
version = VERSION_1_3;
// check for 1.4
Class.forName("java.lang.StackTraceElement");
version = VERSION_1_4;

// check for 1.5
Class.forName("java.lang.Enum");
version = VERSION_1_5;

// check for 1.6
Class.forName("java.lang.management.LockInfo");
version = VERSION_1_6;
}
catch (ClassNotFoundException ignore)
{
}
VERSION = version;
}
/**
* Return the version of Java supported by the VM.
*
* @return The version of Java supported by the VM.
*/
public static int getVersion()
{
return VERSION;
}
/**
* Returns true if the given version identifer is equal to the
* version identifier of the current virtuial machine.
*
* @param version The version identifier to check for.
* @return True if the current virtual machine is the same version.
*/
public static boolean isVersion(final int version)
{
return VERSION == version;
}
/**
* Returns true if the current virtual machine is compatible with
* the given version identifer.
*
* @param version The version identifier to check compatibility of.
* @return True if the current virtual machine is compatible.
*/
public static boolean isCompatible(final int version)
{
// if our vm is the same or newer then we are compatible
return VERSION >= version;
}
}

</source>

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