Introduction to the implementation method of Java traversal (code example)

This article brings you an introduction to the implementation method of Java traversal (code examples), which has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

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();
    }
}

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