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How to get ArrayList to ArrayList
ArrayList<String> to ArrayList<Object>
Instead of the typed parameter in generics (T) you can also use “?”, representing an unknown type. These are known as wild cards you can use a wild card as − Type of parameter or, a Field or, a Local field. Using wild cards, you can convert ArrayList<String> to ArrayList<Object> as −
ArrayList<String> stringList = (ArrayList<String>)(ArrayList<?>)(list);
Example
import java.util.ArrayList;
import java.util.Iterator;
import java.util.ListIterator;
public class ArrayListExample {
public static void main(String args[]) {
//Instantiating an ArrayList object
ArrayList<Object> list = new ArrayList<Object>();
//populating the ArrayList
list.add("apples");
list.add("mangoes");
list.add("oranges");
//Converting the Array list of object type into String type
ArrayList<String> stringList = (ArrayList<String>)(ArrayList<?>)(list);
//listing the contenmts of the obtained list
Iterator<String> it = stringList.iterator();
while(it.hasNext()) {
System.out.println(it.next());
}
}
}Output
apples mangoes oranges
ArrayList<Object> to ArrayList<String>
To convert the ArrayList<Object> to ArrayList<String> −
Create/Get an ArrayList object of String type.
Create a new ArrayList object of Object type by passing the above obtained/created object as a parameter to its constructor.
Example
import java.util.ArrayList;
import java.util.Iterator;
import java.util.ListIterator;
public class ArrayListExample {
public static void main(String args[]) {
//Instantiating an ArrayList object
ArrayList<String> stringList = new ArrayList<String>();
//populating the ArrayList
stringList.add("apples");
stringList.add("mangoes");
stringList.add("oranges");
//Converting the Array list of String type to object type
ArrayList<Object> objectList = new ArrayList<Object>(stringList);
//listing the contents of the obtained list
Iterator<String> it = stringList.iterator();
while(it.hasNext()) {
System.out.println(it.next());
}
}
}Output
apples mangoes oranges
Updated on: 14-Oct-2019
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