Issue in modifying the objects of original list?

Question

I have faced problem temporary list is also modified while original list content is being changed. Expected result should be \'Employ Original\'.

public static v         


        

Answer 1

This would one way of getting a copy of original array.

ArrayList<String> source = new ArrayList<String>();
source.add("test1");
source.add("test2");
ArrayList<String> copyOfSource = new ArrayList<String>();
copyOfSource.addAll(source);

second way is use

Collections.copy(destination, source);

if you dont want your collection to be modified then use

ArrayList<String> source = new ArrayList<String>();
source.add("test1");
source.add("test2");
List<String> immutablelist = Collections.unmodifiableList(source);

Here is the example how it works with custom object

Create a Employee class with two fields, firstName, lastName. Add the getter and setter methods and a constructor.

Employee emp = new Employee("Abhijit","Bashetti");
Employee emp1 = new Employee("Abhijit1","Bashetti1");
Employee emp2 = new Employee("Abhijit2","Bashetti2");

List<Employee> source = new ArrayList<Employee>();
source.add(emp);
source.add(emp1);
source.add(emp2);


ArrayList<Employee> copyOfSource = new ArrayList<Employee>();
copyOfSource.addAll(source);

for (Employee employee : source) {
   System.out.println( "source firstName ::" + employee.getFirstName() + "  source lastName :: " + employee.getLastName());
}

for (Employee employee : copyOfSource) {
   System.out.println( "firstName ::" + employee.getFirstName() + "  lastName :: " + employee.getLastName());
 }

 List<Employee> immutablelist = Collections.unmodifiableList(source);
    for (Employee employee : immutablelist) {
            System.out.println( "firstName ::" + employee.getFirstName() + "  lastName :: " + employee.getLastName());
    }

Answer 2

You need to clone the original objects if you want copies. The ArrayList is only making new pointers for new lists. The pointers still only point to the original objects.