Java example source code file (Utils.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

jdi, numberformatexception, referencetype, string, todo, utils

The Utils.java Java example source code

/*
 * Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */


package com.sun.tools.example.debug.bdi;   //### does it belong here?

import com.sun.jdi.*;

public class Utils {

    /**
     * Return the thread status description.
     */
    public static String getStatus(ThreadReference thr) {
        int status = thr.status();
        String result;
        switch (status) {
          case ThreadReference.THREAD_STATUS_UNKNOWN:
            result = "unknown status";
            break;
          case ThreadReference.THREAD_STATUS_ZOMBIE:
            result = "zombie";
            break;
          case ThreadReference.THREAD_STATUS_RUNNING:
            result = "running";
            break;
          case ThreadReference.THREAD_STATUS_SLEEPING:
            result = "sleeping";
            break;
          case ThreadReference.THREAD_STATUS_MONITOR:
            result = "waiting to acquire a monitor lock";
            break;
          case ThreadReference.THREAD_STATUS_WAIT:
            result = "waiting on a condition";
            break;
          default:
            result = "<invalid thread status>";
        }
        if (thr.isSuspended()) {
            result += " (suspended)";
        }
        return result;
    }

    /**
     * Return a description of an object.
     */
    public static String description(ObjectReference ref) {
        ReferenceType clazz = ref.referenceType();
        long id = ref.uniqueID();  //### TODO use real id
        if (clazz == null) {
            return toHex(id);
        } else {
            return "(" + clazz.name() + ")" + toHex(id);
        }
    }

    /**
     * Convert a long to a hexadecimal string.
     */
    public static String toHex(long n) {
        char s1[] = new char[16];
        char s2[] = new char[18];

        // Store digits in reverse order.
        int i = 0;
        do {
            long d = n & 0xf;
            s1[i++] = (char)((d < 10) ? ('0' + d) : ('a' + d - 10));
        } while ((n >>>= 4) > 0);

        // Now reverse the array.
        s2[0] = '0';
        s2[1] = 'x';
        int j = 2;
        while (--i >= 0) {
            s2[j++] = s1[i];
        }
        return new String(s2, 0, j);
    }

    /**
     * Convert hexadecimal strings to longs.
     */
    public static long fromHex(String hexStr) {
        String str = hexStr.startsWith("0x") ?
            hexStr.substring(2).toLowerCase() : hexStr.toLowerCase();
        if (hexStr.length() == 0) {
            throw new NumberFormatException();
        }

        long ret = 0;
        for (int i = 0; i < str.length(); i++) {
            int c = str.charAt(i);
            if (c >= '0' && c <= '9') {
                ret = (ret * 16) + (c - '0');
            } else if (c >= 'a' && c <= 'f') {
                ret = (ret * 16) + (c - 'a' + 10);
            } else {
                throw new NumberFormatException();
            }
        }
        return ret;
    }


    /*
     * The next two methods are used by this class and by EventHandler
     * to print consistent locations and error messages.
     */
    public static String locationString(Location loc) {
        return  loc.declaringType().name() +
            "." + loc.method().name() + "(), line=" +
            loc.lineNumber();
    }

//### UNUSED.
/************************
    private String typedName(Method method) {
        // TO DO: Use method.signature() instead of method.arguments() so that
        // we get sensible results for classes without debugging info
        StringBuffer buf = new StringBuffer();
        buf.append(method.name());
        buf.append("(");
        Iterator it = method.arguments().iterator();
        while (it.hasNext()) {
            buf.append(((LocalVariable)it.next()).typeName());
            if (it.hasNext()) {
                buf.append(",");
            }
        }
        buf.append(")");
        return buf.toString();
    }
************************/

    public static boolean isValidMethodName(String s) {
        return isJavaIdentifier(s) ||
               s.equals("<init>") ||
               s.equals("<clinit>");
    }

    public static boolean isJavaIdentifier(String s) {
        if (s.length() == 0) {
            return false;
        }
        int cp = s.codePointAt(0);
        if (! Character.isJavaIdentifierStart(cp)) {
            return false;
        }
        for (int i = Character.charCount(cp); i < s.length(); i += Character.charCount(cp)) {
            cp = s.codePointAt(i);
            if (! Character.isJavaIdentifierPart(cp)) {
                return false;
            }
        }
        return true;
    }

}