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 classes import java.util.*;
// Main class public 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 classes import java.util.*;
// Main class public 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]