从键以特定表达式开头的Map中获取所有值的最快方法

如果您使用NavigableMap（例如TreeMap），则可以利用基础树数据结构的好处，并执行以下操作（非常

O(lg(N))

public SortedMap<String, Object> getByPrefix(         NavigableMap<String, Object> myMap,         String prefix ) {    return myMap.subMap( prefix, prefix + Character.MAX_VALUE );}

更扩展的示例：

import java.util.NavigableMap;import java.util.SortedMap;import java.util.TreeMap;public class Test {    public static void main( String[] args ) {        TreeMap<String, Object> myMap = new TreeMap<String, Object>();        myMap.put( "111-hello", null );        myMap.put( "111-world", null );        myMap.put( "111-test", null );        myMap.put( "111-java", null );        myMap.put( "123-one", null );        myMap.put( "123-two", null );        myMap.put( "123--three", null );        myMap.put( "123--four", null );        myMap.put( "125-hello", null );        myMap.put( "125--world", null );        System.out.println( "111 t" + getByPrefix( myMap, "111" ) );        System.out.println( "123 t" + getByPrefix( myMap, "123" ) );        System.out.println( "123-- t" + getByPrefix( myMap, "123--" ) );        System.out.println( "12 t" + getByPrefix( myMap, "12" ) );    }    private static SortedMap<String, Object> getByPrefix( NavigableMap<String, Object> myMap, String prefix ) {        return myMap.subMap( prefix, prefix + Character.MAX_VALUE );    }}

输出为：

111     {111-hello=null, 111-java=null, 111-test=null, 111-world=null}123     {123--four=null, 123--three=null, 123-one=null, 123-two=null}123--   {123--four=null, 123--three=null}12      {123--four=null, 123--three=null, 123-one=null, 123-two=null, 125--world=null, 125-hello=null}