1.場景需求
有一個list<Object>,需要將每個對象的一個屬性(key)對應的值(value)使用一個符號(*@#¥%_-)拼接起來,那麼就可以使用這種方式
代碼:
package com.study.three;
import com.alibaba.fastjson.JSONArray;
import java.util.*;
import java.util.stream.Collectors;
public class three {
public static void main(String[] args) {
List<Apple> list = new ArrayList<>();
for (int i=0 ; i<10; i++){
Apple apple = new Apple();
apple.setName("蘋果"+i);
apple.setWeight("重量"+i);
apple.setColor("顏色"+i);
list.add(apple);
}
//Map appleList = new HashMap<String,Object>();
//appleList.put("list",list);
//ArrayList<Apple> list1 =(ArrayList<Apple>)appleList.get("list");
String str =list.stream().map(n -> n.getName()).collect(Collectors.joining("_"));
System.out.println(str); //打印:蘋果0_蘋果1_蘋果2_蘋果3_蘋果4_蘋果5_蘋果6_蘋果7_蘋果8_蘋果9
}
}
升級版,過濾後再拼接
package com.study.three;
import com.alibaba.fastjson.JSONArray;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class three {
public static void main(String[] args) {
List<Apple> list = new ArrayList<>();
for (int i=0 ; i<10; i++){
Apple apple = new Apple();
apple.setName("蘋果"+i);
apple.setWeight("重量"+i);
apple.setColor("顏色"+i);
list.add(apple);
}
//Map appleList = new HashMap<String,Object>();
//appleList.put("list",list);
//ArrayList<Apple> list1 =(ArrayList<Apple>)appleList.get("list");
String str = list.stream().filter(n -> n.getName().equals("蘋果0")||n.getName().equals("蘋果1")).map(n -> n.getName()).collect(Collectors.joining("_"));
System.out.println(str); //打印:蘋果0_蘋果1
}
}