遍历List<Map<String,Object>>集合
2024-10-21 12:48:02
import java.util.*; public class HelloWorld {
public static void main(String []args) { //定义一个List<Map<String,Object>>集合:
List<Map<String, Object>> listMaps = new ArrayList<Map<String, Object>>(); //定义第一个Map<String,Object>集合,并在其中添加数据
Map<String, Object> map1 = new HashMap<String, Object>();
map1.put("1", "a");
map1.put("2", "b");
map1.put("3", "c");
listMaps.add(map1); //定义第二个Map<String,Object>集合,并在其中添加数据
Map<String, Object> map2 = new HashMap<String, Object>();
map2.put("11", "aa");
map2.put("22", "bb");
map2.put("33", "cc");
listMaps.add(map2); //第一种遍历List<Map<String,Object>>集合的方式
for (Map<String, Object> map : listMaps) {
for (String s : map.keySet()) {
System.out.print(map.get(s) + " ");
}
}
System.out.println(); //打印结果:a b c aa bb cc System.out.println("========================"); //第二种遍历方式
for (int i = 0; i < listMaps.size(); i++) {
Map<String, Object> map = listMaps.get(i);
Iterator iterator = map.keySet().iterator();
while (iterator.hasNext()) {
String string = (String) iterator.next();
System.out.println(map.get(string));
}
}
/**
打印结果:
a
b
c
aa
bb
cc
*/ System.out.println("++++++++++++++++++++++++++++"); //第三种遍历方式
for (Map<String, Object> map : listMaps) {
for (Map.Entry<String, Object> m : map.entrySet()) {
System.out.print(m.getKey() + " ");
System.out.println(m.getValue());
}
}
/**
打印结果:
1 a
2 b
3 c
11 aa
22 bb
33 cc
*/
System.out.println("-----------------------------"); //List<Map<String,Object>>集合 Map<String,Object>集合的区别:
for (Map<String, Object> map : listMaps) {
System.out.println("List<Map>的值:"+ map);
}
/**打印结果:
List<Map>的值:{1=a, 2=b, 3=c}
List<Map>的值:{11=aa, 22=bb, 33=cc}
*/ System.out.println(map1);
//打印结果:{1=a, 2=b, 3=c} //遍历map1集合
for (Map.Entry<String, Object> m : map1.entrySet()) {
System.out.print(m.getKey() + " ");
System.out.println(m.getValue());
}
/**打印结果:
1 a
2 b
3 c
*/ for (Map<String, Object> map : listMaps) {
map.forEach((e, k) -> {
if(e.equals("11")){
k = k + "11";
}
System.out.println("e:"+ e + ",k:" + k);
});
}
/** 打印结果:
e:11,k:aa11
e:22,k:bb
e:33,k:cc
e:1,k:a
e:2,k:b
e:3,k:c
*/ } public void delList(){
// 删除list指定元素
List<Map<String, Object>> products = null;
//获取List元素
products = productService.getProduct();
//使用迭代删除
Iterator<Map<String, Object>> productsIterator = products.iterator();
//hasNext判断是否有元素,next获取元素,“pro01”为键的val
while (productsIterator.hasNext()) {
//删除特定元素
Map<String, Object> product = productsIterator.next();
if("product01".equals(product.get("productName"))){
productsIterator.remove();
}
if("product02".equals(product.get("productName"))){
productsIterator.remove();
}
}
}
}
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