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遍历List和Map集合，遍历数组

2017-04-07 21:31 417 查看

List集合

第一种方法：for-each(加强for循环)

package list;

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

public class ListArray {

public static void main(String[] args) {

List<Object> listArray = new ArrayList<Object>();
listArray.add("唐斐");
listArray.add(521);
listArray.add(new String("简兮"));
for(Object data :listArray){
System.out.println(data);
}
}
}

第二种方法：迭代器

package list;

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

public class ListArray {

public static void main(String[] args) {

List<Object> listArray = new ArrayList<Object>();
listArray.add("唐斐");
listArray.add(521);
listArray.add(new String("简兮"));
Iterator<Object> iterator = listArray.iterator();
while(iterator.hasNext()){
Object data = iterator.next();
System.out.println(data);
}
}
}

第三种方法：jsp/jstl <c:forEach></c:forEach>

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%>
<%@ page import="java.util.List"%>
<%@ page import="java.util.ArrayList"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>List遍历</title>
</head>
<body>
<%
List<String> name = new ArrayList<String>();
name.add("zhangSan");
name.add("liSi");
name.add("wangWu");
name.add("zhaoLiu");
pageContext.setAttribute("ns", name);
%>
<c:forEach var="item" items="${ns }">
<c:out value="name: ${item }"/><br/>
</c:forEach>
</body>
</html>

Map集合：

第一种方法：for-each(加强for循环)

package map;

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

public class MapArray {

public static void main(String[] args) {

Map<Integer,String> hashMap = new HashMap<Integer,String>();
hashMap.put(1, "丹");
hashMap.put(2, "顶");
hashMap.put(3, "鹤");
Set<Integer> setKey = hashMap.keySet();
for	(Integer key : setKey){
String value = hashMap.get(key);
System.out.println(key+"~~~"+value);
}
}
}

第二种方法：迭代器

package map;

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

public class MapArray {

public static void main(String[] args) {

Map<Integer,String> hashMap = new HashMap<Integer,String>();
hashMap.put(1, "丹");
hashMap.put(2, "顶");
hashMap.put(3, "鹤");
Set<Integer> setKey = hashMap.keySet();
Iterator<Integer> iterator = setKey.iterator();
while(iterator.hasNext()){
Integer key = iterator.next();
String value = hashMap.get(key);
System.out.println(key+"~~~"+value);
}
}
}

第三种方法：泛型，类型Entry，for-each(加强for循环)

package map;

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

public class MapArray {

public static void main(String[] args) {

Map<Integer,String> hashMap = new HashMap<Integer,String>();
hashMap.put(1, "丹");
hashMap.put(2, "顶");
hashMap.put(3, "鹤");
Set<Entry<Integer,String>> set = hashMap.entrySet();
for(Entry<Integer,String> entry : set){
Integer key = entry.getKey();
String value = entry.getValue();
System.out.println(key+"~~~"+value);
}

}
}

第四种方法：泛型，类型Entry，迭代器

package map;

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

public class MapArray {

public static void main(String[] args) {

Map<Integer,String> hashMap = new HashMap<Integer,String>();
hashMap.put(1, "丹");
hashMap.put(2, "顶");
hashMap.put(3, "鹤");
Set<Entry<Integer,String>> set = hashMap.entrySet();
Iterator<Entry<Integer,String>> iterator = set.iterator();
while(iterator.hasNext()){
Entry<Integer,String> entry = iterator.next();
Integer key = entry.getKey();
String value = entry.getValue();
System.out.println(key+"~~~"+value);
}
}
}

第五种方法：jsp/jstl <c:forEach></c:forEach>

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%>
<%@ page import="java.util.Map"%>
<%@ page import="java.util.LinkedHashMap"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Map遍历</title>
</head>
<body>
<%
Map<String,String> stu = new LinkedHashMap<String,String>();
stu.put("number", "001");
stu.put("name", "zhangSan");
stu.put("age", "23");
stu.put("sex", "male");
pageContext.setAttribute("stu", stu);
%>
<c:forEach var="item" items="${stu }">
<c:out value="${item.key }: ${item.value }"/><br/>
</c:forEach>
</body>
</html>

遍历数组：

第一种方法：普通for循环

package array;

public class array {

public static void main(String[] args) {

Object [] array = new Object[]{1,"a",new String("d")};
for(int i = 0;i<array.length;i++){
System.out.println(array[i]);
}
}
}

第二种方法：for-each

package array;

public class array {

public static void main(String[] args) {

Object [] array = new Object[]{1,"a",new String("d")};
for(Object data : array){
System.out.println(data);
}
}
}

第三种方法：jsp/jstl <c:forEach></c:forEach>

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>数组遍历</title>
</head>
<body>
<%
String[] name = {"唐斐", "简兮", "安心", "柯洛"};
pageContext.setAttribute("ns", name);
%>
<c:forEach var="item" items="${ns}">
<c:out value="name: ${item}"/><br/>
</c:forEach>
</body>
</html>

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