Constructor Not Used ?

[Jack_Tauson_Sr]

Consider the following Code:

class Node
{
int iData; // data used as key value
double fData; // other data
node leftChild; // this node’s left child
node rightChild; // this node’s right child
public void displayNode()
{
// (see Listing 8.1 for method body)
}
}

class Tree
{
private Node root; // the only data field in Tree
public void find(int key)
{
}
public void insert(int id, double dd)
{
}
public void delete(int id)
{
}
// various other methods
} // end class Tree

class TreeApp
{
public static void main(String[] args)
{
Tree theTree = new Tree; // make a tree
theTree.insert(50, 1.5); // insert 3 nodes
theTree.insert(25, 1.7);
theTree.insert(75, 1.9);
node found = theTree.find(25); // find node with key 25
if(found != null)
System.out.println(“Found the node with key 25”);
else
System.out.println(“Could not find node with key 25”);
} // end main()
} // end class TreeApp

In the above class, TreeApp, why the constructor with no arguments is not called while creating the object of the "Tree" class using the following statement:

Tree theTree = new Tree;


Shouldn't it be like the following?:

Tree theTree = new Tree();

Please state the reason.

Thanks

[JosAH]

Yep, there are parentheses needed there if you want to call the no-arg constructor. That book isn't even worth the trees it's made from ...

kind regards,

Jos

[Jack_Tauson_Sr]

Any other Java book recommended for Algorithms?

[DarrylBurke]

Don't double post the same question. See the moderator remarks in Reference !

db

[kaydell2]

Yes, when you call a constructor, you will always have parentheses.

Also, I found some other problems with the code that you posted:

1. Some places have "node" with a lower-case "n" that should be "Node" with an upper-case "N". "Node" is the class name which begins with an upper-case "N".

2. There were some curly-quotation marks that need to be straight-quotation marks:

System.out.println("Found the node with key 25"); // I fixed this line of code by changing the curly quotes to straight quotes.

3. The method, find() should return a Node rather than having "void" as the return type.