How do I copy a stack in Java?

by

Just use the clone() -method of the Stack-class (it implements Cloneable).

Here’s a simple test-case with JUnit:

@Test   
public void test()
{
    Stack<Integer> intStack = new Stack<Integer>();
    for(int i = 0; i < 100; i++)        
    {
        intStack.push(i);
    }

    Stack<Integer> copiedStack = (Stack<Integer>)intStack.clone();

    for(int i = 0; i < 100; i++)            
    {
        Assert.assertEquals(intStack.pop(), copiedStack.pop());
    }
}

Edit:

tmsimont: This creates a “unchecked or unsafe operations” warning for me. Any
way to do this without generating this problem?

I at first responded that the warning would be unavoidable, but actually it is avoidable using <?> (wildcard) -typing:

@Test
public void test()
{
    Stack<Integer> intStack = new Stack<Integer>();
    for(int i = 0; i < 100; i++)
    {
        intStack.push(i);
    }

    //No warning
    Stack<?> copiedStack = (Stack<?>)intStack.clone();

    for(int i = 0; i < 100; i++)
    {
        Integer value = (Integer)copiedStack.pop(); //Won't cause a warning, no matter to which type you cast (String, Float...), but will throw ClassCastException at runtime if the type is wrong
        Assert.assertEquals(intStack.pop(), value);
    }
}

Basically I’d say you’re still doing an unchecked cast from ? (unknown type) to Integer, but there’s no warning. Personally, I’d still prefer to cast directly into Stack<Integer> and suppress the warning with @SuppressWarnings("unchecked").

More Related Contents:

  1. incompatible types required char found java.lang.string
  2. All possible Angram String combinations in java [closed]
  3. Regex for converting xml tags key to camel case
  4. Change date format in a Java string
  5. Why is Java Vector (and Stack) class considered obsolete or deprecated?
  6. How to split a string with any whitespace chars as delimiters
  7. What is meant by immutable?
  8. What is the purpose of the expression “new String(…)” in Java?
  9. How to convert Java String into byte[]?
  10. How to find nth occurrence of character in a string?
  11. ArrayList initial capacity and IndexOutOfBoundsException [duplicate]
  12. CharSequence VS String in Java?
  13. Java String – See if a string contains only numbers and not letters
  14. Remove trailing zero in Java
  15. Converting String to “Character” array in Java
  16. How can I remove a substring from a given String?
  17. Java String array: is there a size of method?
  18. How to insert Space after every Character of an existing String in Java?
  19. How do I check if a char is a vowel?
  20. Find the Number of Occurrences of a Substring in a String
  21. What is a good 64bit hash function in Java for textual strings?
  22. Reliably convert any object to String and then back again
  23. How to implement a SQL like ‘LIKE’ operator in java?
  24. Query String Manipulation in Java
  25. Java String variable setting – reference or value?
  26. Java generating Strings with placeholders
  27. How is concatenation of final strings done in Java?
  28. How can I remove punctuation from input text in Java?
  29. Is there a difference between String concat and the + operator in Java? [duplicate]
  30. Java String literal pool and string object

Leave a Comment