Reputation: 171

Printing the stack values in Java

In Java, I want to print the contents of a Stack. The toString() method prints them encased in square brackets delimited by commas: [foo, bar, baz].

How do I get rid of them and print the variables only?

My code so far:

Stack myStack = new Stack ();

for(int j=0; j<arrayForVar.length; j++) {
    if(arrayForVar[j][1] != null) {
        System.out.printf("%s \n", arrayForVar[j][1] + "\n");
        myStack.push(arrayForVar[j][1]);
    }
}

System.out.printf("%s \n", myStack.toString());

This answer worked for me:

Use the toString method on the Stack, and use replaceAll method to replace all instances of square brackets with blankstring. Like this:

System.out.print(
    myStack.toString().replaceAll("\\[", "").replaceAll("]", ""));

Upvotes: 15

Answers (12)

Kesava Karri

Reputation: 1004

Since we like imagining the stack from top to bottom, I felt this would be helpful to print a stack without losing the values in the stack :)

public void printStack(Stack<Integer> s) {
    System.out.print("------ stack start ------\n");
    printStackRecursion(s);
    System.out.print("------ stack end ------\n\n");
}

public void printStackRecursion(Stack<Integer> s) {
    if (s.empty()) return;
    int x = s.peek();
    s.pop();
    System.out.println(x);
    printStackRecursion(s);
    s.push(x);
}

Reference: https://www.geeksforgeeks.org/print-stack-elements-from-top-to-bottom/

Upvotes: 0

Ketan sangle

Reputation: 436

Using string builder

StringBuilder result = new StringBuilder()
while(!myStack.isEmpty())result.append(myStack.pop());
System.out.print(result.reverse().toString())

Upvotes: 0

Sói Bé Tí Tì Ti

Reputation: 9

while(!myStack.isEmpty()) {
    System.out.print(myStack.pop());
}

You will print the first element of the stack and pop it, repeating until the stack is empty

Upvotes: 0

Ayoub Bentameur

Reputation: 53

 Stack <String> Cars=new Stack();
 Cars.push("Lambo Urus");
    Cars.push("Honda Civic");
    Cars.push("Ford Mustang");

   while(!Cars.isEmpty()){
                System.out.println(Cars.pop());
            }

Upvotes: -3

Peter

Reputation: 31

Use toArray() to print the stack values

public void printStack(Stack<Integer> stack) {

    // Method 1:
    String values = Arrays.toString(stack.toArray());
    System.out.println(values);

    // Method 2:
    Object[] vals = stack.toArray();
    for (Object obj : vals) {
        System.out.println(obj);
    }
}

Upvotes: 3

VR7

Reputation: 112

Another method is the join method of String which is similar to the join method of Python:

"" + String.join("/", stack)

This will return the string containing all the elements of the stack and we can also add some delimiter by passing in the first argument.

Example: Stack has two elements [home, abc]

Then this will return "/home/abc".

Upvotes: 1

JesseBoyd

Reputation: 1096

stack.forEach(System.out::println);

Using Java 8 and later stream functions

Upvotes: 7

Mohammed salman sayeed

Reputation: 1

Try this:

 System.out.println(Arrays.asList(stackobject.toArray()));
 System.out.println(Arrays.toString(stackobject.toArray()));

Upvotes: -2

John Eipe

Reputation: 11228

There is a workaround.

You could convert it to an array and then print that out with Arrays.toString(Object[]):

System.out.println(Arrays.toString(myStack.toArray()));

Upvotes: 16

Captain Giraffe

Reputation: 14705

Throwing a suggestion into the pool here. Depending on your Stack implementation this may or may not be possible.

The suggestion is an anonymous inner class for overriding the toString() in this particular case. This is one way to locally implement the subclassing Marko is mentioning. Your Stack instantiation would look something like

Stack s = new Stack(){
              public String toString(){
                 // query the elements of the stack, build a string and
                 return nicelyFormattedString;
              }
          };
...

Upvotes: 0

Amit Deshpande

Reputation: 19185

From documentation of toString() method of AbstractCollection. So you can not do it unless you define your own StackOr implement custom toString() by iterating over Stack

public String toString()

Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String.valueOf(Object).

This implementation creates an empty string buffer, appends a left square bracket, and iterates over the collection appending the string representation of each element in turn. After appending each element except the last, the string ", " is appended. Finally a right bracket is appended. A string is obtained from the string buffer, and returned.

Upvotes: 0

Marko Topolnik

Reputation: 200168

Use the same kind of loop that you used to fill the stack and print individual elements to your liking. There is no way to change the behavior of toString, except if you go the route of subclassing Stack, which I wouldn't recommend. If the source code of Stack is under your control, then just fix the implementation of toString there.

Upvotes: 2

Printing the stack values in Java

Answers (12)

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