Java 遍历方法总结

package com.zlh;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class TravelseDemo {

    public static void main(String[] args) {
        // 数组遍历
        System.out.println("1 数组遍历");
        String[] str1 = { "数", "组", "遍", "历" };
        arrayTravelse(str1);
        System.out.println("===================");
        // 字符串遍历
        System.out.println("2 字符串遍历");
        String str2 = "字符串遍历";
        stringTravelse(str2);
        System.out.println("===================");
        // list遍历
        ArrayList<String> list = new ArrayList<String>();
        list.add("集");
        list.add("合");
        list.add("遍");
        list.add("历");
        // list遍历-for-each
        System.out.println("3 list遍历-for-each");
        forTravelse(list);
        System.out.println("===================");
        // list遍历-迭代器
        System.out.println("4 list遍历-迭代器");
        iteratorTravelse(list);
        System.out.println("===================");
        // map遍历
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("jack", 1);
        map.put("tom", 2);
        map.put("jerry", 3);
        // map遍历-for-each与keySet
        System.out.println("5 map遍历-for-each与keySet");
        forKeySetTravelse(map);
        System.out.println("===================");
        // map遍历-迭代器与keySet
        System.out.println("6 map遍历-迭代器与keySet");
        iteratorKeySetTravelse(map);
        System.out.println("===================");
        // map遍历-for-each与entry
        System.out.println("7 map遍历-for-each与entry");
        forEntryTravelse(map);
        System.out.println("===================");
        // map遍历-迭代器与entry
        System.out.println("8 map遍历-迭代器与entry");
        iteratorEntryTravelse(map);
    }

    // 数组遍历
    private static void arrayTravelse(String[] str) {
        for (int i = 0; i < str.length; i++) {
            String j = str[i];
            System.out.print(j + " ");
        }
        System.out.println();
    }

    // 字符串遍历
    private static void stringTravelse(String str) {
        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            System.out.print(c + " ");
        }
        System.out.println();
    }

    // for-each循环遍历
    private static void forTravelse(ArrayList<String> list) {
        for (String str : list) {
            System.out.print(str + " ");
        }
        System.out.println();
    }

    // 迭代器遍历
    private static void iteratorTravelse(ArrayList<String> list) {
        Iterator<String> it = list.iterator();
        while (it.hasNext()) {
            String next = it.next();
            System.out.print(next + " ");
        }
        System.out.println();
    }

    // map遍历-for-each与keySet
    private static void forKeySetTravelse(Map<String, Integer> map) {
        Set<String> set = map.keySet();
        for (String key : set) {
            Integer value = map.get(key);
            System.out.print(key + ":" + value + " ");
        }
        System.out.println();
    }

    // map遍历-迭代器与keySet
    private static void iteratorKeySetTravelse(Map<String, Integer> map) {
        Set<String> set = map.keySet();
        Iterator<String> it = set.iterator();
        while(it.hasNext()) {
            String key = it.next();
            Integer value = map.get(key);
            System.out.print(key + ":" + value + " ");
        }
        System.out.println();
    }
    
    // map遍历-for-each与entry
    private static void forEntryTravelse(Map<String, Integer> map) {
        Set<Entry<String, Integer>> set = map.entrySet();
        for (Map.Entry<String, Integer> entry : set) {
            String key = entry.getKey();
            Integer value = entry.getValue();
            System.out.print(key + ":" + value + " ");
        }
        System.out.println();
    }

    // map遍历-迭代器与entry
    private static void iteratorEntryTravelse(Map<String, Integer> map) {
        Set<Entry<String, Integer>> set = map.entrySet();
        Iterator<Entry<String, Integer>> it = set.iterator();
        while (it.hasNext()) {
            Entry<String, Integer> en = it.next();
            String key = en.getKey();
            Integer value = en.getValue();
            System.out.print(key + ":" + value + " ");
        }
        System.out.println();
    }
}