Binary Trees - Building Java Programs: A Back to Basics Approach - page 1011

q = new Point(-7, -14);
System.out.println("q = " + q);
return q;
}
Then we change the call on the method to the x = change(x) form:
p = change(p);
With these changes, the program produces the following output:
p = java.awt.Point[x=2,y=8]
q = java.awt.Point[x=-7,y=-14]
now p = java.awt.Point[x=-7,y=-14]
The change that occurs in the method propagates back to the main method.
Now let's return to the binary tree add method to see how we could apply this
technique there. Currently the add method has a return type of void :
private void add(IntTreeNode root, int value) {
...
}
We can change it so that the last thing we do in the method is to return the value of
root , which means we have to change the return type to IntTreeNode :
private IntTreeNode add(IntTreeNode root, int value) {
...
return root;
}
Then we change every call on add to match the x = change(x) form. Recall our
old public method:
public void add(int value) {
add(overallRoot, value);
}
The code now becomes:
public void add(int value) {
overallRoot = add(overallRoot, value);
}
The idea is that we pass the value of overallRoot to the add method and it
passes back the value of the parameter, which might be the old value or might be a