我正在尝试使用带有无符号长比较器的树形图。然而，树状图的放置似乎正在删除整个。没有比较器，它工作得很好，但我似乎无法弄清楚比较器出了什么问题。示例代码如下:
公共(public)类主要{
public static void main(String args[]) {
class UnsignComparator implements Comparator<Long> {
@Override
public int compare(Long o1, Long o2) {
if (isLessThanUnsigned(o1, o2)) {
return -1;
} else if (o1.equals(o2)) {
return 0;
} else {
return -1;
}
}
}
TreeMap<Long, String> consistent = new TreeMap<Long, String>(
new UnsignComparator());
System.out.println("Treemap with comparator");
consistent.put(1L, "a");
System.out.println("1L: " + consistent.containsKey(1L));
consistent.put(2L, "b");
System.out.println("1L: " + consistent.containsKey(1L));
System.out.println("2L: " + consistent.containsKey(2L));
consistent.put(3L, "c");
System.out.println("1L: " + consistent.containsKey(1L));
System.out.println("2L: " + consistent.containsKey(2L));
System.out.println("3L: " + consistent.containsKey(3L));
System.out.println("Treemap with comparator keyset");
for (long keys : consistent.keySet()) {
System.out.println(keys);
}
System.out.println("Treemap without comparator");
TreeMap<Long, String> treemap = new TreeMap<Long, String>();
treemap.put(1L, "a");
System.out.println("1L: " + treemap.containsKey(1L));
treemap.put(2L, "b");
System.out.println("1L: " + treemap.containsKey(1L));
System.out.println("2L: " + treemap.containsKey(2L));
treemap.put(3L, "c");
System.out.println("1L: " + treemap.containsKey(1L));
System.out.println("2L: " + treemap.containsKey(2L));
System.out.println("3L: " + treemap.containsKey(3L));
}
//from http://www.javamex.com/java_equivalents/unsigned_arithmetic.shtml
private static boolean isLessThanUnsigned(long n1, long n2) {
return (n1 < n2) ^ ((n1 < 0) != (n2 < 0));
}
}
结果如下:
Treemap with comparator
1L: true
1L: true
2L: true
1L: false //expected true
2L: true
3L: true
Treemap with comparator keyset
3
2
1
Treemap without comparator
1L: true
1L: true
2L: true
1L: true
2L: true
3L: true
最佳答案
else 分支应返回 1，而不是 -1:
@Override
public int compare(Long o1, Long o2) {
if (isLessThanUnsigned(o1, o2)) {
return -1;
} else if (o1.equals(o2)) {
return 0;
} else {
return 1; // <<== HERE: 1, not -1
}
}
关于java - 树状图放置似乎正在删除条目，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16409932/