Foreach loop in java for a custom object list

Question

I have an ArrayList for type Room  my custom object  Defined as below  ArrayList lt Room gt  rooms   new ArrayList lt Room gt       After then adding a series of objects to the ArrayList I want to go through them all and check various things  I am not a keen user of java but I know in many other programming languages a foreach loop would be the most simple way of doing this   After a bit of research I found the following link which suggests the code below  How does the Java   39 for each  39  loop work   for Iterator lt String gt  i   someList iterator    i hasNext          String item   i next      System out println item       But as far as I can tell this cant be used for an Arraylist of a custom object   Can  and if so how can I implement a foreach loop for an ArrayList of a custom object  Or how could I otherwise process each item

User · Answer

You can fix your example with the iterator pattern by changing the parametrization of the class:

List<Room> rooms = new ArrayList<Room>();
rooms.add(room1);
rooms.add(room2);
for(Iterator<Room> i = rooms.iterator(); i.hasNext(); ) {
  String item = i.next();
  System.out.println(item);
}

or much simpler way:

List<Room> rooms = new ArrayList<Room>();
rooms.add(room1);
rooms.add(room2);
for(Room room : rooms) {
  System.out.println(room);
}

User · Answer

Using can also use Java 8 stream API and do the same thing in one line    If you want to print any specific property then use this syntax   ArrayList lt Room gt  rooms   new ArrayList lt  gt     rooms forEach room - gt  System out println room getName        OR  ArrayList lt Room gt  rooms   new ArrayList lt  gt     rooms forEach room - gt           here room is available       if you want to print all the properties of Java object then use this   ArrayList lt Room gt  rooms   new ArrayList lt  gt     rooms forEach System out  println

User · Answer

If this code fails to operate on every item in the list  it must be because something is throwing an exception before you have completed the list  the likeliest candidate is the method called  insertOrThrow   You could wrap that call in a try-catch structure to handle the exception for whichever items are failing without exiting the loop and the method prematurely

User · Answer

for Room room   rooms        room contains an element of rooms

User · Answer

Actually the enhanced for loop should look like this  for  final Room room   rooms                 Here your room is available

[java] Foreach loop in java for a custom object list

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