java 集合处理：

// 1 数组转map
public static void main(String[] args) {String backendIdStr="[\"backend-mvj05upv7yc\",\"backend-mvj055qvric\",\"backend-mvj04hlutx4\"]";String[] backendIdList = JsonUtil.asObject(backendIdStr, String[].class);Stream<String> stream = Arrays.stream(backendIdList);Map<String, String> map = stream.collect(Collectors.toMap(key -> key, value -> value));System.out.println(11111);
}

//  2 List求差集

public static void main(String[] args) {List<String> list1 = new ArrayList<String>();list1.add("A");list1.add("B");List<String> list2 = new ArrayList<String>();list2.add("B");list2.add("C");list1.removeAll(list2);System.out.println("交集:" + list1);//差集:[A]}

// 3 List求交集

public static void main(String[] args) {List<String> list1 = new ArrayList<String>();list1.add("A");list1.add("B");List<String> list2 = new ArrayList<String>();list2.add("B");list2.add("C");list1.retainAll(list2);System.out.println("交集:" + list1);//交集:[B]}

// java 8 处理 ：

public void test1(){

List list1=new ArrayList<>();

list1.add(1);

list1.add(2);

list1.add(3);

List list2=new ArrayList<>();

list2.add(3);

list2.add(4);

list2.add(5);

System.out.println("====求交集===");

List list=list1.stream().filter(t->list2.contains(t)).collect(Collectors.toList());

list.stream().forEach(System.out::println);

System.out.println("====求差集===");

list=list1.stream().filter(t-> !list2.contains(t)).collect(Collectors.toList());

list.stream().forEach(System.out::println);

System.out.println("====求并集===");

list.addAll(list1);

list.addAll(list2);

list=list.stream().distinct().collect(Collectors.toList());

list.stream().forEach(System.out::println);

}