Quellcode-Bibliothek

^© Kompilation durch diese Firma

[Weder Korrektheit noch Funktionsfähigkeit der Software werden zugesichert.]

Datei: NullAtEnd.java Sprache: JAVA

/*
* Copyright (c) 2005, 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.
*/

/*
* @test
* @bug     5018254
* @summary Test null-allowing Comparators
* @author  Martin Buchholz
*/

import java.util.Comparator;
import java.util.SortedMap;
import java.util.TreeMap;

public class NullAtEnd {
    static volatile int passed = 0, failed = 0;

    static void fail(String msg) {
        failed++;
        new AssertionError(msg).printStackTrace();
    }

    static void pass() {
        passed++;
    }

    static void unexpected(Throwable t) {
        failed++;
        t.printStackTrace();
    }

    static void check(boolean condition, String msg) {
        if (condition)
            passed++;
        else
            fail(msg);
    }

    static void check(boolean condition) {
        check(condition, "Assertion failure");
    }

    private static boolean eq(Object x, Object y) {
        return x == null ? y == null : x.equals(y);
    }

    private static final Comparator<String> NULL_AT_END
        = new Comparator<>() {
            /**
             * Allows for nulls.  Null is greater than anything non-null.
             */
            public int compare(String x, String y) {
                if (x == null && y == null) return 0;
                if (x == null && y != null) return 1;
                if (x != null && y == null) return -1;
                return x.compareTo(y);
            }
        };

    public static void main(String[] args) {
        try {
            SortedMap<String,String> m1 = new TreeMap<>(NULL_AT_END);
            check(eq(m1.put("a", "a"), null));
            check(eq(m1.put("b", "b"), null));
            check(eq(m1.put("c", "c"), null));
            check(eq(m1.put(null, "d"), null));

            SortedMap<String,String> m2 = new TreeMap<>(m1);

            check(eq(m1.lastKey(), null));
            check(eq(m1.get(m1.lastKey()), "d"));
            check(eq(m1.remove(m1.lastKey()), "d"));
            check(eq(m1.lastKey(), "c"));

            check(eq(m2.entrySet().toString(), "[a=a, b=b, c=c, null=d]"));

            SortedMap<String,String> m3 = m2.tailMap("b");

            check(eq(m3.lastKey(), null));
            check(eq(m3.get(m3.lastKey()), "d"));
            check(eq(m3.remove(m3.lastKey()), "d"));
            check(eq(m3.lastKey(), "c"));

        } catch (Throwable t) { unexpected(t); }

        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
        if (failed > 0) throw new Error("Some tests failed");
    }
}

¤ Dauer der Verarbeitung: 0.21 Sekunden (vorverarbeitet) ¤

Download des Quellennavigators
Download des sprechenden Kalenders
in der Quellcodebibliothek suchen

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.