In this article, we will discuss how to replace/update content of ArrayList using set method of List interface
This method replaces old value with new value
To replace ArrayList contents with new value :
Method signature:
Object set(int index, Object newObj);
- This method is used to replace/update content of ArrayList element i.e.;
- replacing old value with new value
- returns old object value
ReplaceArrayListContentWithNewValue.java
package in.bench.resources.java.collections; import java.util.ArrayList; public class ReplaceArrayListContentWithNewValue { public static void main(String[] args) { // creating ArrayList object of type String ArrayList<String> tech = new ArrayList<String>(); // adding elements to ArrayList object tech.add("Sun"); tech.add("Apple"); tech.add("JBoss"); tech.add("BEA Weblogic"); tech.add("Apache"); // Iterating using for-loop System.out.println("Iterating ArrayList using for-loop\n"); for(int index = 0; index < tech.size(); index++) { System.out.println("index-" + index + " " + tech.get(index)); } // replacing at 0-th index position tech.set(0, "Oracle"); // replacing at 2-th index position tech.set(2, "Redhat"); // replacing at 3-th index position tech.set(3, "Oracle Weblogic"); // Iterating using enhanced for-loop System.out.println("\n\nIterating after replacing 3-elements\n"); for(String tec : tech) { System.out.println(tec); } } }
Output:
Iterating ArrayList elements using for-loop index-0 Sun index-1 Apple index-2 JBoss index-3 BEA Weblogic index-4 Apache Iterating after replacing 3-elements Oracle Apple Redhat Oracle Weblogic Apache
Exception:
- Trying to set value for out of range index, will throw IndexOutOfBoundsException
- Index should be within range i.e.; 0 <= index < ArrayList size – 1
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 6, Size: 5 at java.util.ArrayList.rangeCheck(ArrayList.java:604) at java.util.ArrayList.set(ArrayList.java:397) at in.bench.resources.java.collections .ReplaceArrayListContentWithNewValue.main (ReplaceArrayListContentWithNewValue.java:32)
References:
- https://docs.oracle.com/javase/tutorial/collections/intro/
- https://docs.oracle.com/javase/tutorial/collections/interfaces/collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Enumeration.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/7/docs/api/java/util/ListIterator.html
Happy Coding !!
Happy Learning !!