JavaInfo.java

package net.ftb.util.winreg;

import java.util.Comparator;

import javax.annotation.Nullable;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

/*
 * Java Finder by petrucio@stackoverflow(828681) is licensed under a Creative Commons Attribution 3.0 Unported License.
 * Needs WinRegistry.java. Get it at: http://stackoverflow.com/questions/62289/read-write-to-windows-registry-using-java
 *
 * JavaFinder - Windows-specific classes to search for all installed versions of java on this system
 * Author: petrucio@stackoverflow (828681)
 *****************************************************************************/

/**
 * Helper struct to hold information about one installed java version
 ****************************************************************************/
public class JavaInfo extends JavaVersion
{
	private static Cache<String, JavaInfo> CACHE;

	static
	{
		CACHE = CacheBuilder.newBuilder().initialCapacity(10).build();
	}

	public String path; // ! Full path to java.exe executable file
	public boolean is64bits; // ! true for 64-bit javas, false for 32

	/**
	 * Creates new JavaInfo using string got from java -version
	 * @param version:
	 ****************************************************************************/
	private JavaInfo (String version) throws Exception
	{
		super(version, true);
	}

	/**
	 * Creates new JavaInfo or returns cached JavaInfo object
	 *
	 * @param javaPath: path to java binary
	 * @return
	 */
	@Nullable
	public static JavaInfo getJavaInfo (String javaPath)
	{
		JavaInfo j = CACHE.getIfPresent(javaPath);
		// TODO: notation to mark that there will not be value for given key?
		if (j == null)
		{
			String output = RuntimeStreamer.execute(new String[]
				{javaPath, "-version"});
			try
			{
				j = new JavaInfo(output);
			}
			catch (Exception e)
			{
				return null;
			}
			j.path = javaPath;
			j.is64bits = output.toUpperCase().contains("64-");
			CACHE.put(javaPath, j);
		}
		return j;
	}

	public boolean samePath (JavaInfo j)
	{
		return this.path.equals(j.path);
	}

	public boolean sameBitness (JavaInfo j)
	{
		return this.is64bits == j.is64bits;
	}

	/**
	 * Tests if JavaInfo are identical: same version, same bitness but not always same path
	 *
	 * Used to manually remove duplicate JavaInfos from Collections
	 * @param j other JavaInfo objct to test
	 * @return
	 */
	public boolean isIdentical (JavaInfo j)
	{
		return (this.isSameVersion(j) && sameBitness(j));
	}

	/**
	 * @return Human-readable contents of this JavaInfo instance
	 ****************************************************************************/
	public String toString ()
	{
		return "Java Version: " + origVersion + " sorted as: " + this.verToString() + " " + (this.is64bits ? "64" : "32") + " Bit Java at : " + this.path;
	}

	public String verToString ()
	{
		return major + "." + minor + "." + revision + "_" + update;
	}

	// PREFERRED sorting compares first bitness then java version
	public static final Comparator<JavaInfo> PREFERRED_SORTING = new Comparator<JavaInfo>()
	{
		public int compare (JavaInfo j1, JavaInfo j2)
		{
			if (!j1.is64bits && j2.is64bits)
			{
				return -1;
			}
			else if (j1.is64bits && !j2.is64bits)
			{
				return 1;
			}
			else
			{
				return j1.comparableVersion.compareTo(j2.comparableVersion);
			}
		}
	};
}