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Order our equals() comparisons in the same way Java Collections do.

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ArrayList and friends explicitly call equals() on the supplied object with the
array object as the argument, rather than the other way around. This allows one
to, for example, pass in some sort of Key object that can compare itself for
equality against a list of KeyedValue objects.

This sort of delicate dance around the equality contract is dangerous, but we
should let the caller decide whether they wish to dance with the devil.
This commit is contained in:
Michael Bayne
2011-09-23 16:26:59 -07:00
parent 7e51d4c624
commit a73908ffad
1 changed files with 16 additions and 20 deletions
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src/main/java/com/samskivert/util/ListUtil.java
+16 -20
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@@ -218,7 +218,7 @@ public class ListUtil
index = i; index = i;
} }
} else if (eqc.equals(elem, element)) { } else if (eqc.equals(element, elem)) {
// oops, it's already in the list // oops, it's already in the list
return null; return null;
} }
@@ -248,7 +248,7 @@ public class ListUtil
/** /**
* Looks for an element that is functionally equal to the supplied * Looks for an element that is functionally equal to the supplied
* element (<code>list[idx].equals(element)</code>). * element (<code>element.equals(list[idx])</code>).
* *
* @return true if a matching element was found, false otherwise. * @return true if a matching element was found, false otherwise.
*/ */
@@ -295,7 +295,7 @@ public class ListUtil
/** /**
* Looks for an element that is functionally equal to the supplied * Looks for an element that is functionally equal to the supplied
* element (<code>list[idx].equals(element)</code>). * element (<code>element.equals(list[idx])</code>).
* *
* @return the index of the matching element if one was found, -1 * @return the index of the matching element if one was found, -1
* otherwise. * otherwise.
@@ -312,7 +312,7 @@ public class ListUtil
requireNotNull(element); requireNotNull(element);
if (list != null) { if (list != null) {
for (int ii = 0, nn = list.length; ii < nn; ii++) { for (int ii = 0, nn = list.length; ii < nn; ii++) {
if (eqc.equals(list[ii], element)) { if (eqc.equals(element, list[ii])) {
return ii; return ii;
} }
} }
@@ -333,7 +333,7 @@ public class ListUtil
/** /**
* Clears out the first element that is functionally equal to the * Clears out the first element that is functionally equal to the
* supplied element (<code>list[idx].equals(element)</code>). * supplied element (<code>element.equals(list[idx])</code>).
* *
* @return the object that was cleared from the array or null if no * @return the object that was cleared from the array or null if no
* matching object was found. * matching object was found.
@@ -372,7 +372,7 @@ public class ListUtil
/** /**
* Removes the first element that is functionally equal to the * Removes the first element that is functionally equal to the
* supplied element (<code>list[idx].equals(element)</code>). The * supplied element (<code>element.equals(list[idx])</code>). The
* elements after the removed element will be slid down the array one * elements after the removed element will be slid down the array one
* spot to fill the place of the removed element. * spot to fill the place of the removed element.
* *
@@ -553,21 +553,17 @@ public class ListUtil
public boolean equals (Object o1, Object o2); public boolean equals (Object o1, Object o2);
} }
protected static final EqualityComparator REFERENCE_COMP = protected static final EqualityComparator REFERENCE_COMP = new EqualityComparator() {
new EqualityComparator() { public boolean equals (Object o1, Object o2) {
public boolean equals (Object o1, Object o2) return o1 == o2;
{ }
return o1 == o2; };
}
};
protected static final EqualityComparator EQUALS_COMP = protected static final EqualityComparator EQUALS_COMP = new EqualityComparator() {
new EqualityComparator() { public boolean equals (Object o1, Object o2) {
public boolean equals (Object o1, Object o2) return ObjectUtil.equals(o1, o2);
{ }
return ObjectUtil.equals(o1, o2); };
}
};
/** /**
* The size of a list to create if we have to create one entirely * The size of a list to create if we have to create one entirely