Skip to main content

Java - Data Structure (Binary Trees)

Binary Trees are one of the fundamental data storage structures used in programming. They provide advantages that the data structures we've seen so far cannot.

Why use binary tree?Usually, because it combines the advantages of two other structures: an ordered and array and a linked list. You can search a tree quickly, as you can with an ordered array, and you can also insert and deleted items quickly,as you can with a linked list.

The disadvantage of an ordered array: slow insertion and deletion.
Disadvantage of a linked list: slow searching.

What is a Tree: A tree consists of nodes connected by edges.
                   O -- Node
                 /    \  --- Edges
               /        \
             O         O
            /  \

In computers programs, nodes often represent such entities as people, car parts, airline reservations, and so on.
Edges are likely to be represented in a program by references, if the program is written in Java( or by pointers if the program is written in C or C++)
class Node{
int iData;
node leftChild;
node rightChild;
}
class Tree{
private Node root;
Node find(key)
}
public Node find(int key){
Node current = root;
while(current.iData != key){
  if(key > current.iData) current = current.leftChild;
  else current = current.rightChild;
if(current == null) return null ; // didn't find it
} // end where
return current;
}

//Successor is left descendant of Right Child of delNode
node getSuccessor(node delNode){
Node successorParent = delNode;
node successor = delNode;
Node current = delNode.rightChild; // go to right child until no more left children
while(current != null){
successorParenet = successor;
successor = current;
current = current.leftChild ; //go to left child if successor not  right child,
}
if(successor != delNode.rightChild) {
successorParent.leftchild = successor.rightChild;
successor.rightChild = delNode.rightChild;
}
 return successor;
}

Comments

Popular posts from this blog

Stretch a row if data overflows in jasper reports

It is very common that some columns of the report need to stretch to show all the content in that column. But  if you just specify the property " stretch with overflow' to that column(we called text field in jasper report world) , it will just stretch that column and won't change other columns, so the row could be ridiculous. Haven't find the solution from internet yet. So I just review the properties in iReport one by one and find two useful properties(the bold highlighted in example below) which resolve the problems.   example:
<band height="20" splitType="Stretch"> <textField isStretchWithOverflow="true" pattern="" isBlankWhenNull="true"> <reportElement stretchType="RelativeToTallestObject" mode="Opaque" x="192" y="0" width="183" height="20"/> <box leftPadding="2"> <pen lineWidth="0.25"/> …

JasperReports - Configuration Reference

Spring - Operations with jdbcTemplate

This class manages all the database communication and exception handling using a java.sql.Connection that is obtained from the provided DataSource. JdbcTemplate is a stateless and threadsafe class and you can safely instantiate a single instance to be used for each DAO.


Use of Callback Methods
JdbcTemplate is based on a template style of programming common to many other parts of Spring. Some method calls are handled entirely by the JdbcTemplate, while others require the calling class to provide callback methods that contain the implementation for parts of the JDBC workflow. This is another form of Inversion of Control. Your application code hands over the responsibility of managing the database access to the template class. The template class in turn calls back to your application code when it needs some detail processing filled in. These callback methods are allowed to throw a java.sql.SQLException, since the framework will be able to catch this exception and use its built-in excepti…