How can I convert ArrayList<Object> to ArrayList?

Answer 1

Your code ArrayList<String> list2 = (String)list; does not compile because list2 is not of type String. But that is not the only problem.

Answer 2

You can use wildcard to do this as following

ArrayList<String> strList = (ArrayList<String>)(ArrayList<?>)(list);

Answer 3

A simple solution:

List<Object> lst  =listOfTypeObject;   
ArrayList<String> aryLst = new ArrayList<String>();
    for (int i = 0; i < lst.size(); i++) {
        aryLst.add(lst.get(i).toString());
    }

Note: this works when the list contains all the elements of datatype String.

Answer 4

Using guava:

List<String> stringList=Lists.transform(list,new Function<Object,String>(){
    @Override
    public String apply(Object arg0) {
        if(arg0!=null)
            return arg0.toString();
        else
            return "null";
    }
});

Answer 5

Using Java 8 you can do:

List<Object> list = ...;
List<String> strList = list.stream()
                           .map( Object::toString )
                           .collect( Collectors.toList() );