java 容器深入研究之使用Abstract类定制

package org.rui.collection3.map;import java.util.AbstractMap;import java.util.AbstractSet;import java.util.ArrayList;import java.util.HashMap;import java.util.HashSet;import java.util.Hashtable;import java.util.Iterator;import java.util.LinkedHashMap;import java.util.LinkedHashSet;import java.util.LinkedList;import java.util.List;import java.util.Map;import java.util.Set;import java.util.TreeMap;import java.util.TreeSet;/*** * 集合 * 使用Abstract类   *  * @author lenovo * */public class Countries{public static final String[][] DATA ={// Africa{ "A", "a" },{ "B", "b" },{ "C", "c" },{ "D", "d" },{ "E", "e" },{ "F", "f" },{ "G", "g" },{ "H", "h" },{ "I", "i" },{ "J", "j" },{ "K", "k" },{ "L", "l" },{ "M", "m" },{ "N", "n" },{ "O", "o" },{ "P", "p" },{ "Q", "q" } };private static class FlyweightMap extends AbstractMap<String, String>{private static class Entry implements Map.Entry<String, String>{int index;Entry(int index){this.index = index;}@Overridepublic String getKey(){return DATA[index][0];}@Overridepublic String getValue(){return DATA[index][1];}@Overridepublic String setValue(String value){throw new UnsupportedOperationException();}public int hashCode(){return index;}public boolean equals(Object o){return DATA[index][0].equals(o);}}// use abstractset by implementing size & iterator 通过实现尺寸& iterato使用套抽象static class EnterSet extends AbstractSet<Map.Entry<String, String>>{private int size;EnterSet(int size) // 享元部分 只存储它的索引 而不是实际的健和值{if (size < 0){this.size = 0;} else if (size > DATA.length){this.size = DATA.length;} else{this.size = size;}}@Overridepublic int size(){return size;}private class Iter implements Iterator<Map.Entry<String, String>>{// 每个迭代器只有一个条目对象private Entry entry = new Entry(-1);@Overridepublic boolean hasNext(){return entry.index < size - 1;}@Overridepublic java.util.Map.Entry<String, String> next(){entry.index++;return entry;}@Overridepublic void remove(){throw new UnsupportedOperationException();}}@Overridepublic Iterator<java.util.Map.Entry<String, String>> iterator(){return new Iter();}}//public static Set<java.util.Map.Entry<String, String>> entries = new EnterSet(DATA.length);@Overridepublic Set<java.util.Map.Entry<String, String>> entrySet(){return entries;}}// create a partial map of size countries 创建一个部分大小国家的地图static Map<String, String> select(final int size){return new FlyweightMap(){@Overridepublic Set<java.util.Map.Entry<String, String>> entrySet(){return new FlyweightMap.EnterSet(size);}};}static Map<String, String> map = new FlyweightMap();public static Map<String, String> capitals(){return map;}public static Map<String, String> capitals(int size){return select(size);// a partial map}static List<String> names = new ArrayList<String>(map.keySet());// all the names;public static List<String> names(){return names;}// A partial listpublic static List<String> names(int size){return new ArrayList<String>(select(size).keySet());}/********************main******************************/public static void main(String[] args){System.out.println(capitals(10));System.out.println(names(10));System.out.println(new HashMap<String, String>(capitals(3)));System.out.println(new TreeMap<String, String>(capitals(3)));System.out.println(new LinkedHashMap<String, String>(capitals(3)));System.out.println(new Hashtable<String, String>(capitals(3)));System.out.println(new HashSet<String>(names(6)));System.out.println(new TreeSet<String>(capitals(6).keySet()));System.out.println(new LinkedHashSet<String>(names(6)));// System.out.println(new Hashtable<String, String>(capitals(3)));System.out.println(new ArrayList<String>(names(6)));System.out.println(new LinkedList<String>(names(6)));System.out.println(capitals().get("F"));}}/**output:{A=a, B=b, C=c, D=d, E=e, F=f, G=g, H=h, I=i, J=j}[A, B, C, D, E, F, G, H, I, J]{A=a, B=b, C=c}{A=a, B=b, C=c}{A=a, B=b, C=c}{A=a, C=c, B=b}[D, E, F, A, B, C][A, B, C, D, E, F][A, B, C, D, E, F][A, B, C, D, E, F][A, B, C, D, E, F]f*/

package org.rui.collection3.map;import java.util.AbstractList;/*** * 它可以具有任意尺寸，并且用Integer数据 有效的 进行了预初始化 * @author lenovo * */public class CountingIntegerList extends AbstractList<Integer>{private int size;public CountingIntegerList(int size){this.size=size<0?0:size;}@Overridepublic Integer get(int index){return Integer.valueOf(index);}@Overridepublic int size(){return size;}public static void main(String[] args){System.out.println(new CountingIntegerList(30));}}/**output: * [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, *  16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29] * */

package org.rui.collection3.map;import java.util.AbstractMap;import java.util.LinkedHashSet;import java.util.Map;import java.util.Set;/** * 这里使用的是LinkedHashSet,而不是定制的Set类，因此享元未完全实现 * @author lenovo * */public class CountingMapData extends AbstractMap<Integer, String>{private int size;private static String[] chars = "A B C D E F G".split(" ");public CountingMapData(int size){if (size < 0)this.size = 0;this.size = size;}private static class Entry implements Map.Entry<Integer, String>{private int index;Entry(int index){this.index = index;}@Overridepublic Integer getKey(){return index;}@Overridepublic String getValue(){return chars[index % chars.length]+ Integer.toString(index / chars.length);}@Overridepublic String setValue(String value){throw new UnsupportedOperationException();}@Overridepublic boolean equals(Object obj){return Integer.valueOf(index).equals(obj);}@Overridepublic int hashCode(){return Integer.valueOf(index).hashCode();}}@Overridepublic Set<java.util.Map.Entry<Integer, String>> entrySet(){// linedhashset 保留初始化顺序Set<Map.Entry<Integer, String>> entries = new LinkedHashSet<Map.Entry<Integer, String>>();for (int i = 0; i < size; i++){entries.add(new Entry(i));}return entries;}public static void main(String[] args){System.out.println(new CountingMapData(60));}}/** * {0=A0, 1=B0, 2=C0, 3=D0, 4=E0, 5=F0, 6=G0, 7=A1,  * 8=B1, 9=C1, 10=D1, 11=E1, 12=F1, 13=G1, 14=A2, 15=B2,  * 16=C2, 17=D2, 18=E2, 19=F2, 20=G2, 21=A3, 22=B3, 23=C3, *  24=D3, 25=E3, 26=F3, 27=G3, 28=A4, 29=B4, 30=C4, 31=D4,  *  32=E4, 33=F4, 34=G4, 35=A5, 36=B5, 37=C5, 38=D5, 39=E5, *   40=F5, 41=G5, 42=A6, 43=B6, 44=C6, 45=D6, 46=E6, 47=F6,  *   48=G6, 49=A7, 50=B7, 51=C7, 52=D7, 53=E7, 54=F7, 55=G7,  *   56=A8, 57=B8, 58=C8, 59=D8} * */