【Java基础之数组与集合】代码库(六)

Map映射.java

/** * get(Object Key) 方法返回指定键所映射的值 * put(K key, V value) 方法来为集合添加数据 */public class CityMap {    public static Map<String, String> model = new LinkedHashMap();    static {            model.put("北京", new String[]{"北京市"});            model.put("上海", new String[]{"上海市"});            model.put("天津", new String[]{"天津市"});            model.put("重庆", new String[]{"重庆市"});    }}public String[] getProvince() {    Map<String, String> map = CityMap.model;    Set<String> st = map.keySet();    String[] province = st.toArray();    return province;}public String[] getCity(String selectedProvince) {    Map<String, String> map = CityMap.model;    String[] arrCity = map.get(selectedProvince);    return arrCity;}

TreeSet 数组.java

/** * TreeSet 集合属于 Set 集合的子类, Set 集合不允许有重复的元素, TreeSet() 类的 add() 方法添加元素： */public class TreeSet {    public static void main(String[] args) {        TreeSet<Integer> tSet = new TreeSet<Integer>();        Random ran = new Random();        int count = 0;        while(count < 10) { //循环生成随机数            boolean succeed = tSet.add(ran.nextInt(100));            if (succeed) {                count++;            }        }        int size = tSet.size();        Integer[] arr = new Integer[size];        tSet.toArray(arr);        System.out.println("生成的不重复随机数组如下： ");        for (int value : arr) {            System.out.print(value + " ");        }    }}

遍历ArrayList.java

import java.util.ArrayList;import java.util.List;public class LocalTest {    public static void main(String[] args) {        List<String> list = new ArrayList<String>();        /** 初始化 List 集合 **/        list.add("abc");        list.add("def");        System.out.println("foreach 遍历集合: ");        for(String string : list) {            System.out.println(string);        }        String[] strs = new String[list.size()];        list.toArray(strs);        System.out.println("foreach 遍历数组: ");        for (String s : strs) {            System.out.println(s);        }    }}