Use a TreeMap
和floorEntry(K key) https://docs.oracle.com/javase/8/docs/api/java/util/TreeMap.html#floorEntry-K- method:
返回与小于或等于给定键的最大键关联的键值映射,或者null
如果没有这样的密钥。
以下是简化的。如果发现无效条目,则实际代码需要搜索,例如如果地图有钥匙0060175551000
,在这种情况下,您需要找到搜索键和找到的键之间的公共前缀,然后再次进行查找。冲洗并重复。
TreeMap<String, String> map = new TreeMap<>();
map.put("0060175559138", "VIP");
map.put("006017555" , "National");
map.put("006017" , "Local");
map.put("0060" , "X");
String key = "0060175552020";
Entry<String, String> entry = map.floorEntry(key);
if (entry == null)
System.out.println("Not found: " + key);
else {
System.out.println(key);
System.out.println(entry);
}
Output
0060175552020
006017555=National
UPDATE有完整的代码,带有用于扩展搜索的循环。
private static Entry<String, String> lookup(NavigableMap<String, String> map, String key) {
String keyToFind = key;
for (;;) {
Entry<String, String> entry = map.floorEntry(keyToFind);
if (entry == null)
return null;
String foundKey = entry.getKey();
int prefixLen = 0;
while (prefixLen < keyToFind.length() && prefixLen < foundKey.length() &&
keyToFind.charAt(prefixLen) == foundKey.charAt(prefixLen))
prefixLen++;
if (prefixLen == 0)
return null;
if (prefixLen == foundKey.length())
return entry;
keyToFind = key.substring(0, prefixLen);
}
}
Test
TreeMap<String, String> map = new TreeMap<>();
map.put("0060175559138", "VIP");
map.put("0060175551000", "Other");
map.put("006017555" , "National");
map.put("006017" , "Local");
map.put("0060" , "X");
System.out.println(lookup(map, "0060175559138"));
System.out.println(lookup(map, "0060175552020"));
System.out.println(lookup(map, "0055708570068"));
System.out.println(lookup(map, "8684064893870"));
Output
0060175559138=VIP
006017555=National
null
null