How to remove specific object from ArrayList in Java

Question

How can I remove specific object from ArrayList  Suppose I have a class as below   import java util ArrayList      public class ArrayTest       int i       public static void main String args             ArrayList lt ArrayTest gt  test new ArrayList lt ArrayTest gt             ArrayTest obj          obj new ArrayTest 1           test add obj           obj new ArrayTest 2           test add obj           obj new ArrayTest 3           test add obj             public ArrayTest int i           this i i            How can I remove object with new ArrayTest 1  from my ArrayList lt ArrayList gt

User · Accepted Answer

ArrayList removes objects based on the equals Object obj  method  So you should implement properly this method  Something like   public boolean equals Object obj        if  obj    null  return false      if  obj    this  return true      if    obj instanceof ArrayTest   return false      ArrayTest o    ArrayTest  obj      return o i    this i      Or  public boolean equals Object obj        if  obj instanceof ArrayTest            ArrayTest o    ArrayTest  obj          return o i    this i            return false

User · Answer

I have tried this and it works for me   ArrayList lt cartItem gt  cartItems  new ArrayList lt  gt        filling the cartItems  cartItem ci new cartItem itemcode itemQuantity    the one I want to remove  Iterator lt cartItem gt  itr  cartItems iterator    while  itr hasNext        cartItem ci itr itr next       if  ci itr getClass      ci getClass           itr remove          return

User · Answer

ArrayTest obj new ArrayTest 1       test add obj       ArrayTest obj1 new ArrayTest 2       test add obj1       ArrayTest obj2 new ArrayTest 3       test add obj2        test remove object of ArrayTest     you can specify how you control each object

User · Answer

Here is full example  we have to use  Iterator s remove   method  import java util ArrayList  import java util Iterator   public class ArrayTest       int i      public static void main String args              ArrayList lt ArrayTest gt  test   new ArrayList lt ArrayTest gt             ArrayTest obj          obj   new ArrayTest 1           test add obj           obj   new ArrayTest 2           test add obj           obj   new ArrayTest 3           test add obj           System out println  Before removing size is     test size       And Element are       test           Iterator lt ArrayTest gt  itr   test iterator            while  itr hasNext                  ArrayTest number   itr next                if  number i    1                    itr remove                                    System out println  After removing size is     test size       And Element are      test             public ArrayTest int i            this i   i             Override     public String toString             return  ArrayTest  i     i

User · Answer

You can use Collections binarySearch to find the element  then call remove on the returned index   See the documentation for Collections binarySearch here  http   docs oracle com javase 1 4 2 docs api java util Collections html binarySearch 28java util List  20java lang Object 29  This would require the ArrayTest object to have  equals implemented though   You would also need to call Collections sort to sort the list   Finally  ArrayTest would have to implement the Comparable interface  so that binarySearch would run correctly   This is the  proper  way to do it in Java   If you are just looking to solve the problem in a quick and dirty fashion  then you can just iterate over the elements and remove the one with the attribute you are looking for

User · Answer

List lt Object gt  list   new ArrayList    for  Iterator lt Object gt  iterator   list iterator    iterator hasNext         Object obj  iterator next        if  obj getId   equals  1                Remove the current element from the iterator and the list         iterator remove

User · Answer

or you can use java 8 lambda test removeIf i - gt  i  2   it will simply remove all object that meet the condition

User · Answer

For removing the particular object from arrayList there are two ways  Call the function of arrayList    Removing on the basis of the object    arrayList remove object     This will remove your object but in most cases when arrayList contains the items of UserDefined DataTypes  this method does not give you the correct result  It works fine only for Primitive DataTypes  Because user want to remove the item on the basis of object field value and that can not be compared by remove function automatically    Removing on the basis of specified index position of arrayList  The best way to remove any item or object from arrayList  First  find the index of the item which you want to remove  Then call this arrayList method  this method removes the item on index basis  And it will give the correct result    arrayList remove index

User · Answer

This helped me           card temperaryCardFour   theDeck get theDeck size   - 1           theDeck remove temperaryCardFour         instead of   theDeck remove numberNeededRemoved     I got a removal conformation on the first snippet of code and an un removal conformation on the second   Try switching your code with the first snippet I think that is your problem   Nathan Nelson

User · Answer

If you are using Java 8   test removeIf t - gt  t i    1     Java 8 has a removeIf method in the collection interface  For the ArrayList  it has an advanced implementation  order of n

User · Answer

simple use remove   function  and pass object as param u want to remove  ur arraylist remove obj

User · Answer

If you want to remove multiple objects that are matching to the property try this   I have used following code to remove element from object array it helped me   In general an object can be removed in two ways from an ArrayList  or generally any List   by index  remove int   and by object  remove Object     some time for you arrayList remove index or arrayList remove obj get index   using these lines may not work try to use following code   for  Iterator lt DetailInbox gt  iter   detailInboxArray iterator    iter hasNext            DetailInbox element   iter next       if  element isSelected            iter remove

User · Answer

use this code  test remove test indexOf obj     test is your ArrayList and obj is the Object  first you find the index of obj in ArrayList and then you remove it from the ArrayList

User · Answer

In general an object can be removed in two ways from an ArrayList  or generally any List   by index  remove int   and by object  remove Object     In this particular scenario  Add an equals Object  method to your ArrayTest class  That will allow ArrayList remove Object  to identify the correct object

User · Answer

AValchev is right  A quicker solution would be to parse all elements and compare by an unique property    String property    property to delete    for int j   0  j  lt  i size    j          Student obj   i get j        if obj getProperty   equals property             found  delete          i remove j           break             THis is a quick solution  You d better implement object comparison for larger projects

[java] How to remove specific object from ArrayList in Java?

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