How to determine whether list is empty in java?

Java method to determine whether the collection list is empty:

If you want to determine whether the list is empty , it can be judged like this:

if(list == null || list.size() ==0 ){
　　//为空的情况
}else{
　　//不为空的情况
}

The difference between list.isEmpty() and list.size()==0

Answer: No difference . isEmpty() determines whether there are elements, and size() returns how many elements there are. If you determine whether a collection has elements, it is recommended to use the isEmpty() method. It is more logical usage.

isEmpty() also determines whether there are elements in the list collection. If there are elements, it returns false. If there is no element, it returns true. If the collection itself is set to null, a null pointer exception will be reported.

list! =null Follow ! What is the difference between list.isEmpty()?

This is equivalent to if you want to go to the store to buy something

list! =null First determine whether there is a store

! list.isEmpty() does not determine whether the store exists, but determines whether the store has items

Summary usage: If there is no store, how can anything be sold?

So the general judgment It’s

if(list!=null && !list.isEmpty()){
　　　//不为空的情况
}else{
　　　//为空的情况
}

Recommended learning: Java video tutorial

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