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OpenSearch subproject :distribution:tools:java-version-checker

There is a newer version: 2.18.0

/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.tools.java_version_checker;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

public class JavaVersion {

    public static final List CURRENT = parse(System.getProperty("java.specification.version"));
    public static final List JAVA_8 = parse("1.8");
    public static final List JAVA_11 = parse("11");

    static List parse(final String value) {
        if (!value.matches("^0*[0-9]+(\\.[0-9]+)*$")) {
            throw new IllegalArgumentException(value);
        }

        final List version = new ArrayList();
        final String[] components = value.split("\\.");
        for (final String component : components) {
            version.add(Integer.valueOf(component));
        }
        return version;
    }

    public static int majorVersion(final List javaVersion) {
        Objects.requireNonNull(javaVersion);
        if (javaVersion.get(0) > 1) {
            return javaVersion.get(0);
        } else {
            return javaVersion.get(1);
        }
    }

    static int compare(final List left, final List right) {
        // lexicographically compare two lists, treating missing entries as zeros
        final int len = Math.max(left.size(), right.size());
        for (int i = 0; i < len; i++) {
            final int l = (i < left.size()) ? left.get(i) : 0;
            final int r = (i < right.size()) ? right.get(i) : 0;
            if (l < r) {
                return -1;
            }
            if (r < l) {
                return 1;
            }
        }
        return 0;
    }

}