键值对使用

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第一种类型<String>之类的

List<Integer> list = new ArrayList<Integer>();list.add(1);list.add(2);list.add(3);list.add(4);

第二种类型<Object>对象

class Person{String name;String address;public Person(String name, String address) {this.name = name;this.address = address;}}List<Person> list2=new ArrayList<Person>();Person person = new Person("tom", "北京");Person person2 = new Person("jim","上海");Person person3 = new Person("kim","宁波");list2.add(person);list2.add(person2);list2.add(person3);

第三种Map< , >

Map<String, String> student = new HashMap<String, String>();student.put("name", "tom");student.put("address", "北京");Set<String> keys= student.keySet();Iterator<String> iterator=keys.iterator();while(iterator.hasNext()){System.out.println(iterator.next());}

第四种与第二种效果一样,表达方式不同

List<Map<String,String>> list4 = new ArrayList<Map<String, String>>();Map<String, String> map1 = new HashMap<String,String>();map1.put("name","tom");map1.put("address", "北京");Map<String, String> map2 = new HashMap<String,String>();map2.put("name","jim");map2.put("address", "上海");Map<String, String> map3 = new HashMap<String,String>();map3.put("name","kim");map3.put("address", "宁波");list4.add(map1);list4.add(map2);list4.add(map3);

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