Find tools.jar if it exists on your system, translated from https://stackoverflow.com/a/25163628

FindToolsJar.java

import java.util.*;
import java.io.File;

class FindToolsJar {
    static ArrayList<String> paths = new ArrayList<String>();
    static ArrayList<File> files = new ArrayList<File>();
    static final String suffix = "/lib/tools.jar";

    private static final void addStringToArray(String value) {
        try {
            if (value != null && !value.isEmpty())
                paths.add(value);
        } catch (Exception e) {
            ;
        }
    }

    public static void main(String[] args) {
        addStringToArray(System.getenv("JDK_HOME"));
        addStringToArray(System.getenv("JAVA_HOME"));
        addStringToArray(System.getProperty("java.home"));

        try {
            File file = new File(System.getProperty("java.home"));
            addStringToArray(file.getParent());
        } catch (Exception e) {
            ;
        }

        for (String path : paths) {
            try {
                File file = new File(path + suffix);
                System.out.println(file.getAbsolutePath());
                System.exit(0);
            } catch (Exception e) {
                System.out.println("Could not automatically find JDK/lib/tools.jar");
                System.exit(1);
            }
        }


    }
}

Compile with javac -target 1.5 -source 1.5 FindToolsJar.java which will produce a FindToolsJar.class file that will run with any Java version 1.5 or newer. You can then simply run with java FindToolsJar to find the location of tools.jar. You can also do java -classpath folder FindToolsJar if FindToolsJar.class is located in folder.

The idea behind this script is to quickly and easily locate the tools.jar which some Java instrumentation tools require to be on the classpath of your running application. Since Java is portable across different operating systems (and is always going to be located on a machine that runs JDK), the script was written itself in Java.