- Java.util Package Classes
- Java.util - Home
- Java.util - ArrayDeque
- Java.util - ArrayList
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- Java.util - BitSet
- Java.util - Calendar
- Java.util - Collections
- Java.util - Currency
- Java.util - Date
- Java.util - Dictionary
- Java.util - EnumMap
- Java.util - EnumSet
- Java.util - Formatter
- Java.util - GregorianCalendar
- Java.util - HashMap
- Java.util - HashSet
- Java.util - Hashtable
- Java.util - IdentityHashMap
- Java.util - LinkedHashMap
- Java.util - LinkedHashSet
- Java.util - LinkedList
- Java.util - ListResourceBundle
- Java.util - Locale
- Java.util - Observable
- Java.util - PriorityQueue
- Java.util - Properties
- Java.util - PropertyPermission
- Java.util - PropertyResourceBundle
- Java.util - Random
- Java.util - ResourceBundle
- Java.util - ResourceBundle.Control
- Java.util - Scanner
- Java.util - ServiceLoader
- Java.util - SimpleTimeZone
- Java.util - Stack
- Java.util - StringTokenizer
- Java.util - Timer
- Java.util - TimerTask
- Java.util - TimeZone
- Java.util - TreeMap
- Java.util - TreeSet
- Java.util - UUID
- Java.util - Vector
- Java.util - WeakHashMap
- Java.util Package Extras
- Java.util - Interfaces
- Java.util - Exceptions
- Java.util - Enumerations
- Java.util Useful Resources
- Java.util - Useful Resources
- Java.util - Discussion
Java Collections replaceAll() Method
Description
The Java Collections replaceAll(List<T>, T, T) method is used to replace all occurrences of one specified value in a list with another.
Declaration
Following is the declaration for java.util.Collections.replaceAll() method.
public static <T> boolean replaceAll(List<T> list,T oldVal,T newVal)
Parameters
list − This is the list in which replacement is to occur.
oldVal − This is the old value to be replaced.
newVal − This is the new value with which oldVal is to be replaced.
Return Value
The method call returns 'true' if list contained one or more elements e such that (oldVal==null ? e==null : oldVal.equals(e)).
Exception
UnsupportedOperationException − This is thrown if the specified list or its list-iterator does not support the set operation.
Replacing All Instances of a Value with Given Value From a List of Integers Example
The following example shows the usage of Java Collection replaceAll(List, T, T) method. We've created a list object, populated it with some integers. Then its one of the value is replaced and then result is printed.
package com.tutorialspoint; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String[] args) { List<Integer> list = new ArrayList<>(Arrays.asList(3,2,3,3,5)); System.out.println("Initial collection value: " + list); // replace all 3 of this collection Collections.replaceAll(list, 3, 1); System.out.println("Final collection value: "+list); } }
Output
Let us compile and run the above program, this will produce the following result −
Initial collection value: [3, 2, 3, 3, 5] Final collection value: [1, 2, 1, 1, 5]
Replacing All Instances of a Value with Given Value From a List of Strings Example
The following example shows the usage of Java Collection replaceAll(List, T, T) method. We've created a list object, populated it with some strings. Then its one of the value is replaced and then result is printed.
package com.tutorialspoint; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String[] args) { List<String> list = new ArrayList<>(Arrays.asList("C","B","C","C")); System.out.println("Initial collection value: " + list); // replace C of this collection Collections.replaceAll(list, "C","A"); System.out.println("Final collection value: "+list); } }
Output
Let us compile and run the above program, this will produce the following result −
Initial collection value: [C, B, C, C] Final collection value: [A, B, A, A]
Replacing All Instances of a Value with Given Value From a List of Objects Example
The following example shows the usage of Java Collection replaceAll(List, T, T) method. We've created a list object, populated it with some Student objects. Then its one of the value is replaced and then result is printed.
package com.tutorialspoint; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String[] args) { List<Student> list = new ArrayList<>(Arrays.asList(new Student(1, "Julie"), new Student(2, "Robert"), new Student(3, "Adam"), new Student(1, "Julie"), new Student(1, "Julie"))); System.out.println("Initial collection value: " + list); // replace Julie with null in this collection Collections.replaceAll(list, new Student(1, "Julie"), null); System.out.println("Final collection value: "+list); } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } }
Output
Let us compile and run the above program, this will produce the following result −
Initial collection value: [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ], [ 1, Julie ], [ 1, Julie ]] Final collection value: [null, [ 2, Robert ], [ 3, Adam ], null, null]
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