package com.unionpay.service.channelbankcard.impl;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class Test {
public static void main(String[] args) {
Map<String,String> map=new HashMap<String,String>();
map.put("key1", "value1");
map.put("key2", "value2");
map.put("key3", "value3");
map.put("key4", "value4");
///第一种:通过Map.keySet遍历key和value,普遍使用,二次取值
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
//第二种 通过Map.entrySet使用iterator遍历key和value
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第三种:推荐,尤其是容量大时 通过Map.entrySet遍历key和value
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第四种 通过Map.values()遍历所有的value,但不能遍历key
for (String v : map.values()) {
System.out.println("value= " + v);
}
}
}
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class Test {
public static void main(String[] args) {
Map<String,String> map=new HashMap<String,String>();
map.put("key1", "value1");
map.put("key2", "value2");
map.put("key3", "value3");
map.put("key4", "value4");
///第一种:通过Map.keySet遍历key和value,普遍使用,二次取值
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
//第二种 通过Map.entrySet使用iterator遍历key和value
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第三种:推荐,尤其是容量大时 通过Map.entrySet遍历key和value
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第四种 通过Map.values()遍历所有的value,但不能遍历key
for (String v : map.values()) {
System.out.println("value= " + v);
}
}
}