Java中数组、List、Set互相转换

数组转list

string[] staffs = new string[]{"tom", "bob", "jane"};
list staffslist = arrays.aslist(staffs);

• 需要注意的是， arrays.aslist() 返回一个受指定数组决定的固定大小的列表。所以不能做 add 、 remove 等操作，否则会报错。

  list staffslist = arrays.aslist(staffs);
  staffslist.add("mary"); // unsupportedoperationexception
  staffslist.remove(0); // unsupportedoperationexception

• 如果想再做增删操作呢？将数组中的元素一个一个添加到列表，这样列表的长度就不固定了，可以进行增删操作。

  list staffslist = new arraylist<string>();
  for(string temp: staffs){
    staffslist.add(temp);
  }
  staffslist.add("mary"); // ok
  staffslist.remove(0); // ok

---

数组转set

string[] staffs = new string[]{"tom", "bob", "jane"};
set<string> staffsset = new hashset<>(arrays.aslist(staffs));
staffsset.add("mary"); // ok
staffsset.remove("tom"); // ok

---

list转数组

string[] staffs = new string[]{"tom", "bob", "jane"};
list staffslist = arrays.aslist(staffs);

object[] result = staffslist.toarray();

---

list转set

string[] staffs = new string[]{"tom", "bob", "jane"};
list staffslist = arrays.aslist(staffs);

set result = new hashset(staffslist);

---

set转数组

string[] staffs = new string[]{"tom", "bob", "jane"};
set<string> staffsset = new hashset<>(arrays.aslist(staffs));

object[] result = staffsset.toarray();

---

set转list

string[] staffs = new string[]{"tom", "bob", "jane"};
set<string> staffsset = new hashset<>(arrays.aslist(staffs));

list<string> result = new arraylist<>(staffsset);