练习代码（八）对象的集合（二）

迷南。 2022-08-03 00:56 170阅读 0赞

1.容器的打印

package first;
    
    import java.util.*;
    
    
    public class PrintingContainers {
    
        //定义一个方法接受Collection对象，来保存对象.
    
        static Collection fill(Collection c){
            c.add("dog");
            c.add("dog");
            c.add("cat");
            return c;
        }
    
        //定义一个方法接受Map对象，来保存对象.
    
        static Map fill(Map m){
            m.put("sky", "blue");
            m.put("flower","red");
            m.put("river", "green");
            return m;
        }
    
        public static void main(String[] args){
    
          //调用fill()方法来打印容器内容.
    
            //创建一个List类型的对象，让其打印List类型的容器(List类型要求元素按一定顺序排列).
    
            System.out.println(fill(new ArrayList()));
    
            //创建一个Set类型的对象，让其打印Set类型的容器(Set类型要求元素不能有重复).
    
            System.out.println(fill(new HashSet()));
    
            //创建一个Map类型的对象，让其打印Map类型的容器(Map类型要求元素成对有关联的出现).
    
            System.out.println(fill(new HashMap()));
    
        }
    
    }

2.填充容器

package c112;
    
    import java.util.*;
    
    public class FillingLists {
    
        public static void main(String[] args){
    
            List list = new ArrayList();
    
            for(int i = 0; i < 10; i++){
                list.add("");
            Collections.fill(list, "Hello");
            System.out.println(list);
    
            }
    
        }
    
    }

3.封装改写Collections2类

package c112;
    
    public class Pair { 
    
        public Object key,value;
    
        public Pair(Object k,Object v){
            key = k;
            value = v;
        }
    
    }
    
    package c112;
    
    public interface MapGenerator{ 
        Pair next();
    }
    
    package c112;
    
    import java.util.Collection;
    import java.util.Map;
    
    import second.*;
    
    public class Collections2 { 
    
        public static void fill(Collection c,Generator gen,int count){
    
            for(int i = 0; i < count; i++ )
                c.add(gen.next());
    
        }
    
        public static void fill(Map m,MapGenerator gen,int count){
    
            for(int i = 0; i < count; i++){
    
                Pair p = gen.next();
                m.put(p.key, p.value);
    
            }
    
        }
    
        public static class RandStringPairGenerator implements MapGenerator{ 
    
            private static Arrays2.RandStringGenerator rsg;
    
            public RandStringPairGenerator(int length){ 
    
                rsg = new Arrays2.RandStringGenerator(length);
    
            }
    
            @Override
            public Pair next() {
                // TODO Auto-generated method stub
    
                return new Pair(rsg.next(),rsg.next());
    
            }
    
        }
    
        public static RandStringPairGenerator rspg = new RandStringPairGenerator(5);
    
    
        public static class StringPairGenerator implements MapGenerator{ 
    
            private int index = -1;
            private String[][] d;
    
            public StringPairGenerator(String[][] data){
    
                d = data;
    
            }
    
            @Override
            public Pair next() {
                // TODO Auto-generated method stub
    
                index = (index+1)%d.length;
                return new Pair(d[index][0],d[index][1]);
    
            }
    
            public StringPairGenerator reset(){
    
                index = -1;
                return this;
    
            }
        }
            //public static MapGenerator geography;
            public static StringPairGenerator geography = new StringPairGenerator(CountryCapitals.pairs);
    
            public static class StringGenerator implements Generator{ 
    
                private String[][] d;
                private int position;
                private int index = 1;
                public StringGenerator(String[][] data, int pos){
    
                    d = data;
                    position = pos;
    
                }
    
                public Object next(){
    
                    index = (index+1)%d.length;
                    return d[index][position];
    
                }
    
                public StringGenerator reset(){
    
                    index = -1;
                    return this;
    
                }
    
            }
    
            public static StringGenerator countries = new StringGenerator(CountryCapitals.pairs,0);
            public static StringGenerator capitals = new StringGenerator(CountryCapitals.pairs,1);
    
    }
    
    //定义国家和首都的集合
    package c112;
    
    public class CountryCapitals { 
    
        public   static    final String[][] pairs = {
    
            // Africa
    
                {
       "ALGERIA","Algiers"}, {
       "ANGOLA","Luanda"},
    
                {
       "BENIN","Porto-Novo"}, {
       "BOTSWANA","Gaberone"},
    
                {
       "BURKINA FASO","Ouagadougou"},
    
                {
       "BURUNDI","Bujumbura"},
    
                {
       "CAMEROON","Yaounde"}, {
       "CAPE VERDE","Praia"},
    
                {
       "CENTRAL AFRICAN REPUBLIC","Bangui"},
    
                {
       "CHAD","N'djamena"},  {
       "COMOROS","Moroni"},
    
                {
       "CONGO","Brazzaville"}, {
       "DJIBOUTI","Dijibouti"},
    
                {
       "EGYPT","Cairo"}, {
       "EQUATORIAL GUINEA","Malabo"},
    
                {
       "ERITREA","Asmara"}, {
       "ETHIOPIA","Addis Ababa"},
    
                {
       "GABON","Libreville"}, {
       "THE GAMBIA","Banjul"},
    
                {
       "GHANA","Accra"}, {
       "GUINEA","Conakry"},
    
                {
       "GUINEA","-"}, {
       "BISSAU","Bissau"},
    
                {
       "COTE D'IVOIR (IVORY COAST)","Yamoussoukro"},
    
                {
       "KENYA","Nairobi"}, {
       "LESOTHO","Maseru"},
    
                {
       "LIBERIA","Monrovia"}, {
       "LIBYA","Tripoli"},
    
                {
       "MADAGASCAR","Antananarivo"}, {
       "MALAWI","Lilongwe"},
    
                {
       "MALI","Bamako"}, {
       "MAURITANIA","Nouakchott"},
    
                {
       "MAURITIUS","Port Louis"}, {
       "MOROCCO","Rabat"},
    
                {
       "MOZAMBIQUE","Maputo"}, {
       "NAMIBIA","Windhoek"},
    
                {
       "NIGER","Niamey"}, {
       "NIGERIA","Abuja"},
    
                {
       "RWANDA","Kigali"},
    
                {
       "SAO TOME E PRINCIPE","Sao Tome"},
    
                {
       "SENEGAL","Dakar"}, {
       "SEYCHELLES","Victoria"},
    
                {
       "SIERRA LEONE","Freetown"}, {
       "SOMALIA","Mogadishu"},
    
                {
       "SOUTH AFRICA","Pretoria/Cape Town"},
    
                {
       "SUDAN","Khartoum"},
    
                {
       "SWAZILAND","Mbabane"}, {
       "TANZANIA","Dodoma"},
    
                {
       "TOGO","Lome"}, {
       "TUNISIA","Tunis"},
    
                {
       "UGANDA","Kampala"},
    
                {
       "DEMOCRATIC REPUBLIC OF THE CONGO (ZAIRE)",
    
            "Kinshasa"},
    
                {
       "ZAMBIA","Lusaka"}, {
       "ZIMBABWE","Harare"},
    
            // Asia
    
                {
       "AFGHANISTAN","Kabul"}, {
       "BAHRAIN","Manama"},
    
                {
       "BANGLADESH","Dhaka"}, {
       "BHUTAN","Thimphu"},
    
                {
       "BRUNEI","Bandar Seri Begawan"},
    
                {
       "CAMBODIA","Phnom Penh"},
    
                {
       "CHINA","Beijing"}, {
       "CYPRUS","Nicosia"},
    
                {
       "INDIA","New Delhi"}, {
       "INDONESIA","Jakarta"},
    
                {
       "IRAN","Tehran"}, {
       "IRAQ","Baghdad"},
    
                {
       "ISRAEL","Tel Aviv"}, {
       "JAPAN","Tokyo"},
    
                {
       "JORDAN","Amman"}, {
       "KUWAIT","Kuwait City"},
    
                {
       "LAOS","Vientiane"}, {
       "LEBANON","Beirut"},
    
                {
       "MALAYSIA","Kuala Lumpur"}, {
       "THE MALDIVES","Male"},
    
                {
       "MONGOLIA","Ulan Bator"},
    
                {
       "MYANMAR (BURMA)","Rangoon"},
    
                {
       "NEPAL","Katmandu"}, {
       "NORTH KOREA","P'yongyang"},
    
                {
       "OMAN","Muscat"}, {
       "PAKISTAN","Islamabad"},
    
                {
       "PHILIPPINES","Manila"}, {
       "QATAR","Doha"},
    
                {
       "SAUDI ARABIA","Riyadh"}, {
       "SINGAPORE","Singapore"},
    
                {
       "SOUTH KOREA","Seoul"}, {
       "SRI LANKA","Colombo"},
    
                {
       "SYRIA","Damascus"},
    
                {
       "TAIWAN (REPUBLIC OF CHINA)","Taipei"},
    
                {
       "THAILAND","Bangkok"}, {
       "TURKEY","Ankara"},
    
                {
       "UNITED ARAB EMIRATES","Abu Dhabi"},
    
                {
       "VIETNAM","Hanoi"}, {
       "YEMEN","Sana'a"},
    
            // Australiaand Oceania
    
                {
       "AUSTRALIA","Canberra"}, {
       "FIJI","Suva"},
    
                {
       "KIRIBATI","Bairiki"},
    
                {
       "MARSHALL ISLANDS","Dalap-Uliga-Darrit"},
    
                {
       "MICRONESIA","Palikir"}, {
       "NAURU","Yaren"},
    
                {
       "NEW ZEALAND","Wellington"}, {
       "PALAU","Koror"},
    
                {
       "PAPUA NEW GUINEA","Port Moresby"},
    
                {
       "SOLOMON ISLANDS","Honaira"}, {
       "TONGA","Nuku'alofa"},
    
                {
       "TUVALU","Fongafale"}, {
       "VANUATU","< Port-Vila"},
    
                {
       "WESTERN SAMOA","Apia"},
    
            // EasternEurope and former USSR
    
                {
       "ARMENIA","Yerevan"}, {
       "AZERBAIJAN","Baku"},
    
                {
       "BELARUS (BYELORUSSIA)","Minsk"},
    
                {
       "GEORGIA","Tbilisi"},
    
                {
       "KAZAKSTAN","Almaty"}, {
       "KYRGYZSTAN","Alma-Ata"},
    
                {
       "MOLDOVA","Chisinau"}, {
       "RUSSIA","Moscow"},
    
                {
       "TAJIKISTAN","Dushanbe"}, {
       "TURKMENISTAN","Ashkabad"},
    
                {
       "UKRAINE","Kyiv"}, {
       "UZBEKISTAN","Tashkent"},
    
            // Europe
    
                {
       "ALBANIA","Tirana"}, {
       "ANDORRA","Andorra la Vella"},
    
                {
       "AUSTRIA","Vienna"}, {
       "BELGIUM","Brussels"},
    
                {
       "BOSNIA","-"}, {
       "HERZEGOVINA","Sarajevo"},
    
                {
       "CROATIA","Zagreb"}, {
       "CZECH REPUBLIC","Prague"},
    
                {
       "DENMARK","Copenhagen"}, {
       "ESTONIA","Tallinn"},
    
                {
       "FINLAND","Helsinki"}, {
       "FRANCE","Paris"},
    
                {
       "GERMANY","Berlin"}, {
       "GREECE","Athens"},
    
                {
       "HUNGARY","Budapest"}, {
       "ICELAND","Reykjavik"},
    
                {
       "IRELAND","Dublin"}, {
       "ITALY","Rome"},
    
                {
       "LATVIA","Riga"}, {
       "LIECHTENSTEIN","Vaduz"},
    
                {
       "LITHUANIA","Vilnius"}, {
       "LUXEMBOURG","Luxembourg"},
    
                {
       "MACEDONIA","Skopje"}, {
       "MALTA","Valletta"},
    
                {
       "MONACO","Monaco"}, {
       "MONTENEGRO","Podgorica"},
    
                {
       "THE NETHERLANDS","Amsterdam"}, {
       "NORWAY","Oslo"},
    
                {
       "POLAND","Warsaw"}, {
       "PORTUGAL","Lisbon"},
    
                {
       "ROMANIA","Bucharest"}, {
       "SAN MARINO","San Marino"},
    
                {
       "SERBIA","Belgrade"}, {
       "SLOVAKIA","Bratislava"},
    
                {
       "SLOVENIA","Ljujiana"}, {
       "SPAIN","Madrid"},
    
                {
       "SWEDEN","Stockholm"}, {
       "SWITZERLAND","Berne"},
    
                {
       "UNITED KINGDOM","London"}, {
       "VATICAN CITY","---"},
    
            // North andCentral America
    
                {
       "ANTIGUA AND BARBUDA","Saint John's"},
    
                {
       "BAHAMAS","Nassau"},
    
                {
       "BARBADOS","Bridgetown"}, {
       "BELIZE","Belmopan"},
    
                {
       "CANADA","Ottawa"}, {
       "COSTA RICA","San Jose"},
    
                {
       "CUBA","Havana"}, {
       "DOMINICA","Roseau"},
    
                {
       "DOMINICAN REPUBLIC","Santo Domingo"},
    
                {
       "EL SALVADOR","San Salvador"},
    
                {
       "GRENADA","Saint George's"},
    
                {
       "GUATEMALA","Guatemala City"},
    
                {
       "HAITI","Port-au-Prince"},
    
                {
       "HONDURAS","Tegucigalpa"}, {
       "JAMAICA","Kingston"},
    
                {
       "MEXICO","Mexico City"}, {
       "NICARAGUA","Managua"},
    
                {
       "PANAMA","Panama City"}, {
       "ST. KITTS","-"},
    
                {
       "NEVIS","Basseterre"}, {
       "ST. LUCIA","Castries"},
    
                {
       "ST. VINCENT AND THE GRENADINES","Kingstown"},
    
                {
       "UNITED STATES OF AMERICA","Washington, D.C."},
    
            // SouthAmerica
    
                {
       "ARGENTINA","Buenos Aires"},
    
                {
       "BOLIVIA","Sucre (legal)/La Paz(administrative)"},
    
                {
       "BRAZIL","Brasilia"}, {
       "CHILE","Santiago"},
    
                {
       "COLOMBIA","Bogota"}, {
       "ECUADOR","Quito"},
    
                {
       "GUYANA","Georgetown"}, {
       "PARAGUAY","Asuncion"},
    
                {
       "PERU","Lima"}, {
       "SURINAME","Paramaribo"},
    
                {
       "TRINIDAD AND TOBAGO","Port of Spain"},
    
                {
       "URUGUAY","Montevideo"}, {
       "VENEZUELA","Caracas"},
    
              };
    
    
    
    }

4.测试容器中元素的类型

package c112;
    
    public class Cat {
    
        private int catNumber;
    
        public Cat(int i){
            catNumber = i;
        }
    
        public void id(){
            System.out.println("Cat #"+catNumber);
        }
    }
    
    package c112;
    
    public class Dog {
    
        private int dogNumber;
    
        public Dog(int i){
            dogNumber = i;
        }
    
        public void id(){
            System.out.println("Dog #"+dogNumber);
        }
    
    }
    
    package c112;
    
    import java.util.*;
    
    public class CatAndDog {
    
        public static void main(String[] args){
    
            List list = new ArrayList();
            for(int i = 0; i < 7; i++)
                list.add(new Cat(i));
            list.add(new Dog(7));
            for(int i = 0; i < list.size(); i++)
            ((Cat)list.get(i)).id();
        }
    
    }

5.制作一个类型明确的ArrayList

public class MouseList{
        private List list = new ArrayList();
        public void add(Mouse m){
            list.add(m);
        }
        publlic Mouse get(int index){
            return (Mouse)list.get(index);
        }
        public int size(){
            return list.size();
        }
    }

6.迭代器

package c112;
    
    import java.util.*;
    
    public class CatAndDog { 
    
        public static void main(String[] args){
    
            List list = new ArrayList();
            for(int i = 0; i < 7; i++)
                list.add(new Cat(i));
            Iterator e = list.iterator();
             while(e.hasNext())
             ((Cat)e.next()).id();
    
        }
    
    }