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Java example source code file (Arguments.java)

This example Java source code file (Arguments.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

address, addressfield, arguments, object, observer, string, stringbuilder, type, util

The Arguments.java Java example source code

/*
 * Copyright (c) 2004, 2006, 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.
 *
 * 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.
 *
 */

package sun.jvm.hotspot.runtime;

import java.util.*;

import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.utilities.*;

/** This class represent VM's Arguments class -- command line args, flags etc.*/
public class Arguments {
    static {
        VM.registerVMInitializedObserver(new Observer() {
            public void update(Observable o, Object data) {
                initialize(VM.getVM().getTypeDataBase());
            }
        });
    }

    public static String getJVMFlags() {
        return buildString(jvmFlagsField, jvmFlagsCount);
    }

    public static String getJVMArgs() {
        return buildString(jvmArgsField, jvmArgsCount);
    }

    public static String getJavaCommand() {
        return getString(javaCommandField);
    }

    // Internals only below this point

    // Fields
    private static AddressField jvmFlagsField;
    private static AddressField jvmArgsField;
    private static AddressField javaCommandField;
    private static long jvmFlagsCount;
    private static long jvmArgsCount;

    private static synchronized void initialize(TypeDataBase db) {
        Type argumentsType = db.lookupType("Arguments");
        jvmFlagsField = argumentsType.getAddressField("_jvm_flags_array");
        jvmArgsField = argumentsType.getAddressField("_jvm_args_array");
        javaCommandField = argumentsType.getAddressField("_java_command");

        jvmArgsCount = argumentsType.getCIntegerField("_num_jvm_args").getValue();
        jvmFlagsCount = argumentsType.getCIntegerField("_num_jvm_flags").getValue();
    }

    private static String buildString(AddressField arrayField, long count) {
        StringBuilder sb = new StringBuilder();
        if (count > 0) {
            sb.append(getStringAt(arrayField, 0));
            for (long i = 1; i < count; i++) {
                sb.append(" ");
                sb.append(getStringAt(arrayField, i));
            }
        }
        return sb.toString();
    }

    private static String getString(AddressField field) {
        Address addr = field.getAddress();
        return CStringUtilities.getString(addr);
    }

    private static String getStringAt(AddressField field, long index) {
        Address addr = field.getAddress();
        return CStringUtilities.getString(addr.getAddressAt(index * VM.getVM().getAddressSize()));
    }
}

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