有关集合类和泛型结合-

ArrayList 和 Iterator

package cn.edu.bupt;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class ArrayListTest {
    public static void main(String[] args) {
        //List和ArrayList是泛型
        List<String> list = new ArrayList<String>();
        
        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        
        for(String e: list) {
            System.out.println(e);
        }
        //Iterator变成泛型
        for(Iterator<String> itr = list.iterator();itr.hasNext();) {
            String value = itr.next();
            System.out.println(value);
        }
    }
}

HashSet和Iterator

package cn.edu.bupt1;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class SetTest {
    public static void main(String[] args) {
        Set<String> set = new HashSet<String>();
        set.add("aa");
        set.add("bb");
        set.add("cc");
        
        for(Iterator<String> itr = set.iterator(); itr.hasNext();) {
            String value = itr.next();
            System.out.println(value);
        }
        
        System.out.println("----------------------");
        
        Set<Person> set1 = new HashSet<Person>();
        
        set1.add(new Person("zhangsan", 20, "beijing"));
        set1.add(new Person("lisi", 30, "shanghai"));
        set1.add(new Person("wangwu", 40, "nanjing"));
        
        for(Person p: set1) {
            System.out.println(p.getName());
            System.out.println(p.getAge());
            System.out.println(p.getAddress());
        }
    }
}

class Person {
    private String name;
    private int age;
    private String address;
    
    public Person(String name, int age, String address) {
        super();
        this.name = name;
        this.age = age;
        this.address = address;
    }
    
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((address == null) ? 0 : address.hashCode());
        result = prime * result + age;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Person other = (Person) obj;
        if (address == null) {
            if (other.address != null)
                return false;
        } else if (!address.equals(other.address))
            return false;
        if (age != other.age)
            return false;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        return true;
    }

    //setter and getter
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

Map与Iterator

package cn.edu.bupt;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class MapTest {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<String, String>();
        
        map.put("a", "aa");
        map.put("b", "bb");
        map.put("c", "cc");
        
        //first method of getting the value in map using Set
        Set<String> keys = map.keySet();
        for(String str: keys) {
            System.out.println(map.get(str));
        }
        
        //second method of getting the value in map using Map.Entry<K, V>
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        for(Map.Entry<String, String> entry: entrySet) {
            System.out.println(entry.getKey() + "=>" + entry.getValue());
        }
    }
}