Collections.replaceAll in Java
June 27, 2022
Collections.replaceAll method.
1. The
replaceAll is a static method of java.util.Collections class.
2. The
Collections.replaceAll replaces all occurrences of a specified value from the given value in a list.
3. Find the method declaration.
static <T> boolean replaceAll(List<T> list, T oldVal, T newVal)
(oldVal==null ? e==null : oldVal.equals(e))
Type Parameters:
T is the class of the objects in the list.
Parameters:
The list is the list in which replacement is to occur.
The oldVal is the old value to be replaced.
The newVal is the new value with which oldVal is to be replaced.
Returns: Returns true if list contained one or more elements e such that
(oldVal==null ? e==null : oldVal.equals(e))
Throws: If the specified list does not support operation, method throws
UnsupportedOperationException.
Example-1
List<String> list = new ArrayList<>();
list.add("Mahesh");
list.add("Suresh");
list.add("Mahesh");
String oldVal = "Mahesh";
String newVal = "Shiva";
Collections.replaceAll(list, oldVal, newVal);
System.out.println(list);
[Shiva, Suresh, Shiva]
Example-2
List<Integer> list = new ArrayList<>(); list.add(20); list.add(15); list.add(20); int oldVal = 20; int newVal = 30; Collections.replaceAll(list, oldVal, newVal); System.out.println(list);
[30, 15, 30]
Example-3
List<Integer> list = new ArrayList<>(); list.add(null); list.add(15); list.add(null); Integer oldVal = null; int newVal = 30; Collections.replaceAll(list, oldVal, newVal); System.out.println(list);
[30, 15, 30]
