Collections.emptyList in Java
February 04, 2022
Collections.emptyList method.
static final <T> List<T> emptyList()
emptyList returns an immutable empty list.
2. In immutable list, we cannot add or remove elements.
3. The use of empty list is that if our method is returning empty list, create it by
Collections.emptyList method.
4. Immutable empty list performance is faster than
new ArrayList().
5. The
emptyList is used as following.
List<String> list = Collections.emptyList();
Example
CollectionsEmpty.java
package com.concretepage.util;
import java.util.Collections;
import java.util.List;
public class CollectionsEmpty {
int row = getRowFromDB();
//immutable empty List
public List<String> getDataInList(){
List<String> list = null;
if (row == 0) {
list = Collections.emptyList();
}
return list;
}
private int getRowFromDB() {
int cnt = 0; //access DB to calculate rows
//returns DB rows
return cnt;
}
}
