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src/java.base/share/classes/java/lang/StringBuilder.java
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@@ -1,7 +1,7 @@
/*
- * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2018, 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
@@ -67,18 +67,26 @@
*
* <p>Unless otherwise noted, passing a {@code null} argument to a constructor
* or method in this class will cause a {@link NullPointerException} to be
* thrown.
*
+ * @apiNote
+ * {@code StringBuilder} implements {@code Comparable} but does not override
+ * {@link Object#equals equals}. Thus, the natural ordering of {@code StringBuilder}
+ * is inconsistent with equals. Care should be exercised if {@code StringBuilder}
+ * objects are used as keys in a {@code SortedMap} or elements in a {@code SortedSet}.
+ * See {@link Comparable}, {@link java.util.SortedMap SortedMap}, or
+ * {@link java.util.SortedSet SortedSet} for more information.
+ *
* @author Michael McCloskey
* @see java.lang.StringBuffer
* @see java.lang.String
* @since 1.5
*/
public final class StringBuilder
extends AbstractStringBuilder
- implements java.io.Serializable, CharSequence
+ implements java.io.Serializable, Comparable<StringBuilder>, CharSequence
{
/** use serialVersionUID for interoperability */
static final long serialVersionUID = 4383685877147921099L;
@@ -128,10 +136,35 @@
public StringBuilder(CharSequence seq) {
this(seq.length() + 16);
append(seq);
}
+ /**
+ * Compares two {@code StringBuilder} instances lexicographically. This method
+ * follows the same rules for lexicographical comparison as defined in the
+ * {@linkplain java.lang.CharSequence#compare(java.lang.CharSequence,
+ * java.lang.CharSequence) CharSequence.compare(this, another)} method.
+ *
+ * <p>
+ * For finer-grained, locale-sensitive String comparison, refer to
+ * {@link java.text.Collator}.
+ *
+ * @param another the {@code StringBuilder} to be compared with
+ *
+ * @return the value {@code 0} if this {@code StringBuilder} contains the same
+ * character sequence as that of the argument {@code StringBuilder}; a negative integer
+ * if this {@code StringBuilder} is lexicographically less than the
+ * {@code StringBuilder} argument; or a positive integer if this {@code StringBuilder}
+ * is lexicographically greater than the {@code StringBuilder} argument.
+ *
+ * @since 11
+ */
+ @Override
+ public int compareTo(StringBuilder another) {
+ return super.compareTo(another);
+ }
+
@Override
public StringBuilder append(Object obj) {
return append(String.valueOf(obj));
}
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