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OneCodeOneTimeOneCodeOneTime
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Chapter 17 collections btp170710
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‎Study.iml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<module type="JAVA_MODULE" version="4">
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<component name="NewModuleRootManager" inherit-compiler-output="true">
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<exclude-output />
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<content url="file://$MODULE_DIR$">
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<sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
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</content>
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<orderEntry type="inheritedJdk" />
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<orderEntry type="sourceFolder" forTests="false" />
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<orderEntry type="library" name="lib1" level="project" />
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</component>
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</module>

‎src/btp/oneP/ABtpTest.java‎

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import java.io.PrintStream;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Scanner;
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public class ABtpTest {
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PrintStream p = System.out;
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Scanner sc =new Scanner(System.in);
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try{
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ArrayList as = returnArray();
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/*ArrayList as = returnArray();
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ArrayList<String> ass = (ArrayList<String>)as;
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p.println(ass);
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as = returnArrayNew();
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p.println(as);
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ass = (ArrayList<String>)as;
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p.println(ass);
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p.println(ass);*/
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List myIntList = new LinkedList();//1
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myIntList.add(new Integer(0));//2
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Integer x = (Integer) myIntList.iterator().next();//3
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}catch(Exception e){
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e.printStackTrace();
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}finally{

‎src/btp/oneP/CollectionMethod.java‎

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package btp.oneP;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.List;
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public class CollectionMethod {
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public static void main(String[] args) {
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Collection<String> c = new ArrayList<String>();
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c.addAll(Countries.names(6));
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c.add("ten");
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c.add("eleven");
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System.out.println(c);
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Object[] array = c.toArray();
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String[] str = c.toArray(new String[0]);
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System.out.println(Arrays.toString(array));
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System.out.println(Arrays.toString(str));
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System.out.println("Collections.max(c) = "+Collections.max(c));
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System.out.println("Collections.min(c) = "+Collections.min(c));
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Collection<String> c2 = new ArrayList<String>();
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c2.addAll(Countries.names(6));
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c.addAll(c2);
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System.out.println(c);
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c.remove(Countries.DATA[0][0]);
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System.out.println(c);
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c.removeAll(c2);
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System.out.println(c);
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c.addAll(c2);
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System.out.println(c);
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String val = Countries.DATA[3][0];
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System.out.println("c.contains("+val+")="+c.contains(val));
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System.out.println("c.containsAll(c2)="+c.containsAll(c2));
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Collection<String> c3 = ((List<String>)c).subList(3, 5);
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c2.retainAll(c3);
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System.out.println(c2);
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c2.removeAll(c3);
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System.out.println("c2.isEmpty()="+c2.isEmpty());
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c = new ArrayList<String>();
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c.addAll(Countries.names(6));
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System.out.println(c);
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c.clear();
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System.out.println("after c.clear():"+c);
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}
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}

‎src/btp/oneP/CountingIntegerList.java‎

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package btp.oneP;
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import java.util.AbstractList;
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public class CountingIntegerList extends AbstractList<Integer>{
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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//构造函数构造对象时里面还没有值，都是null，在调用toString函数的时候，
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//toString函数内使用Iterator遍历集合，next()时调用了get(index)
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//所以是边赋值边打印
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System.out.println(new CountingIntegerList(30));
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}
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private int size;
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public CountingIntegerList(int size){
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this.size = size<0?0:size;
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}
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@Override
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public Integer get(int index) {
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// TODO Auto-generated method stub
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return Integer.valueOf(index);
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}
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@Override
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public int size() {
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// TODO Auto-generated method stub
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return size;
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}
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}

‎src/btp/oneP/CountingMapData.java‎

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package btp.oneP;
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import java.util.AbstractMap;
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import java.util.LinkedHashSet;
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import java.util.Map;
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import java.util.Set;
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public class CountingMapData extends AbstractMap<Integer,String>{
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public static void main(String...args){
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System.out.println(new CountingMapData(60));
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}
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private int size;
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private static String[] chars = "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z".split(" ");
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public CountingMapData(int size){
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this.size = size<0?0:size;
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}
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private static class Entry implements Map.Entry<Integer, String>{
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int index;
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Entry(int index){
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this.index = index;
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}
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public boolean equals(Object o){
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return Integer.valueOf(index).equals(o);
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}
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@Override
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public Integer getKey() {
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// TODO Auto-generated method stub
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return index;
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}
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@Override
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public String getValue() {
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// TODO Auto-generated method stub
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return chars[index%chars.length]+Integer.toString(index/chars.length);
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}
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@Override
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public String setValue(String value) {
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// TODO Auto-generated method stub
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return null;
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}
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public int hashCode(){
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return Integer.valueOf(index).hashCode();
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}
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}
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@Override
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public Set<java.util.Map.Entry<Integer, String>> entrySet() {
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// TODO Auto-generated method stub
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Set<Map.Entry<Integer, String>> entries = new LinkedHashSet<Map.Entry<Integer,String>>();
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for(int i=0;i<size;i++){
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entries.add(new Entry(i));
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}
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return entries;
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}
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}

‎src/btp/oneP/Countries.java‎

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package btp.oneP;
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import java.util.AbstractMap;
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import java.util.AbstractSet;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Hashtable;
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import java.util.Iterator;
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import java.util.LinkedHashMap;
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import java.util.LinkedHashSet;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Map;
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import java.util.Set;
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import java.util.TreeMap;
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import java.util.TreeSet;
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public class Countries {
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public static void main(String[] args) {
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System.out.println(capitals(10));
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System.out.println(names(10));
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System.out.println(new HashMap<String,String>(capitals(3)));
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System.out.println(new LinkedHashMap<String,String>(capitals(3)));
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System.out.println(new TreeMap<String,String>(capitals(3)));
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System.out.println(new Hashtable<String,String>(capitals(3)));
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System.out.println(new HashSet<String>(names(6)));
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System.out.println(new LinkedHashSet<String>(names(6)));
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System.out.println(new TreeSet<String>(names(6)));
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System.out.println(new ArrayList<String>(names(6)));
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System.out.println(new LinkedList<String>(names(6)));
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System.out.println(capitals().get("ALGERIA"));
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}
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public static final String[][] DATA = {
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{"ALGERIA","Algiers"},{"CHINA","Beijing"},
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{"Japan","Tokoy"},{"America","Washington"}
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};
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private static class FlyweightMap extends AbstractMap<String,String>{
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private static class Entry implements Map.Entry<String, String>{
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int index;
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Entry(int index){
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this.index = index;
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}
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public boolean equals(Object o){
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return DATA[index][0].equals(o);
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}
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@Override
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public String getKey() {
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// TODO Auto-generated method stub
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return DATA[index][0];
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}
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@Override
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public String getValue() {
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return DATA[index][1];
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}
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@Override
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public String setValue(String value) {
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// TODO Auto-generated method stub
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return null;
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}
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public int hashCode(){
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return DATA[index][0].hashCode();
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}
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}
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static class EntrySet extends AbstractSet<Map.Entry<String, String>>{
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private int size;
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EntrySet(int size){
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if(size < 0){
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this.size = 0;
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}else if(size > DATA.length){
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this.size = DATA.length;
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}else{
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this.size = size;
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}
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}
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public int size(){
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return size;
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}
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@Override
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public Iterator<java.util.Map.Entry<String, String>> iterator() {
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// TODO Auto-generated method stub
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return new Iter();
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}
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private class Iter implements Iterator<Map.Entry<String, String>>{
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private Entry entry = new Entry(-1);
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@Override
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public boolean hasNext() {
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// TODO Auto-generated method stub
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return entry.index < size - 1;
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}
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@Override
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public java.util.Map.Entry<String, String> next() {
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entry.index++;
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return entry;
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}
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}
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}
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private static Set<Map.Entry<String, String>> entries = new EntrySet(DATA.length);
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@Override
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public Set<java.util.Map.Entry<String, String>> entrySet() {
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return entries;
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}
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}
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static Map<String,String> select(final int size){
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return new FlyweightMap(){
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public Set<Map.Entry<String, String>> entrySet(){
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return new EntrySet(size);
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}
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};
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}
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static Map<String,String> map = new FlyweightMap();
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public static Map<String,String> capitals(){
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return map;
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}
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public static Map<String,String> capitals(int size){
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return select(size);
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}
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static List<String> names = new ArrayList<String>(map.keySet());
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public static List<String> names(){
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return names;
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}
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public static List<String> names(int size){
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return new ArrayList<String>(select(size).keySet());
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}
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}

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