我有一个具有以下结构的Collection对象:
[
{
"maBN": 8,
"address": "American",
"_type": "Person",
"name": "Anna Johnson",
"parent_of": [
{
"maBN": 10,
"address": "American",
"_type": "Person",
"name": "Abraham Napoleon",
"parent_of.type": "natural",
"_id": 63
},
{
"maBN": 11,
"address": "American",
"_type": "Person",
"name": "William Napoleon",
"parent_of.type": "natural",
"_id": 64
}
],
"_id": 61
}
]
我要检查它是否为空:
[
{}
]
这是我要检查的功能:
public Collection<Object> getFamilyTree(@RequestParam Long id, @RequestParam String gender) {
if (personService.getFamilyTree(id,gender).toArray().length!=0)
{
return personService.getFamilyTree(id, gender);
}
else{
return personService.getFamilyTree2Gen(id,gender);
}
}
与personService.getFamilyTree和personService.getFamilyTree2Gen一起返回集合
我该怎么办?非常感谢,抱歉我的英语不好!
答案 0 :(得分:0)
使用下面的实用程序方法了解集合是否为空或空。
public static <T> boolean isEmpty(Collection<T> c) {
if (c == null) {
return true;
} else {
return c.size() == 0;
}
}
public static <T> boolean isNotEmpty(Collection<T> c) {
return !isEmpty(c);
}
然后像这样在您的代码中写
Collection<Object> familyTree = personService.getFamilyTree(id, gender);
if (isNotEmpty(familyTree)) {
return familyTree;
} else {
return personService.getFamilyTree2Gen(id,gender);
}