Collections replaceAll() Method in Java with Examples
The replaceAll() method of java.util.Collections class is used to replace all occurrences of one specified value in a list with another. More formally, replaces with newVal each element e in the list such that
oldVal == null ? e==null : oldVal.equals(e)
Note: This method has no effect on the size of the list.
Parameters: This method takes the following argument as a Parameter
- list: The list in which replacement is to occur.
- oldVal: The old value to be replaced.
- newVal: The new value with which oldVal is to be replaced.
Return Value: This method returns true if the list contained one or more elements e such that as shown below else false
oldVal== null ? e==null : oldVal.equals(e)
Syntax:
public static boolean replaceAll(List list, T oldVal, T newVal)
Example 1:
Java
// Java program to demonstrate// replaceAll() method for String value// Importing utility classesimport java.util.*;// Main classpublic class GFG { // Main driver method public static void main(String[] argv) throws Exception { // Try block to check for exceptions try { // Creating a vector object of string type List<String> vector = new Vector<String>(); // Populating the above Vector object // Custom input elements vector.add("A"); vector.add("B"); vector.add("A"); vector.add("C"); // Printing the vector System.out.println("Initial Vector :" + vector); // Replacing value // using replaceAll() method Collections.replaceAll(vector, "A", "TAJMAHAL"); // Printing elements of Vector object after // replacing System.out.println("Vector after replace :" + vector); } // Catch block to handle the exceptions catch (IllegalArgumentException e) { // Display message when exception occurs System.out.println("Exception thrown : " + e); } }} |
Output
Initial Vector :[A, B, A, C] Vector after replace :[TAJMAHAL, B, TAJMAHAL, C]
Example 2:
Java
// Java program to demonstrate// replaceAll() method for Integer value// importing utility classesimport java.util.*;// Main classpublic class GFG { // Main driver method public static void main(String[] argv) throws Exception { // Try block to check for exceptions try { // Creating object of List<String> List<Integer> vector = new Vector<Integer>(); // Populate the vector vector.add(20); vector.add(30); vector.add(20); vector.add(30); // Printing the vector before replacing // elements System.out.println("Initial values are :" + vector); // Replacing value // using replaceAll() method Collections.replaceAll(vector, 20, 400); // Printing the vector after replacing elements System.out.println("Value after replace :" + vector); } // Catch block to handle IllegalArgumentException catch (IllegalArgumentException e) { // Display the exceptions on the console System.out.println("Exception thrown : " + e); } }} |
Output:
Initial values are :[20, 30, 20, 30] Value after replace :[400, 30, 400, 30]
