Samreen Dhillon

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COMS W3137 RecitationFebruary 20 08

• Samreen Dhillon

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Agenda

• Java Swings
• GUI components
• DisplaySimpleTree.java(http//www1.cs.columbia.edu
  /allen/S08/NOTES/DisplaySimpleTree.java)
• GUI components used
• Tree routines
• Algorithm

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Java Swings

• Widget Toolkit for Java
• Provides GUI to java programs
• Lightweight
• More sophisticated GUI components than AWT
• Pluggable look and feel itself draws the GUI
  components
• MVC (Model View Controller) architecture

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GUI Components

• JFrame
• Extension of java.awt.Frame
• ContentPane - should contain all non-menu items
• frame.getContentPane().add(child)
• ContentPane is never null
• setDefaultCloseOperation()
• pack()

public class DisplaySimpleTree extends JFrame
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GUI Components

• JPanel
• PaintComponent(Graphics g)
• Revalidate() update the panel
• Graphics
• Draw on components
• drawString()
• g.drawString("Binary Search tree for the input
  string\n",xs,ys)
• drawLine()
• g.drawLine(dx,dy,dx2,dy2)

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Binary Tree

• Tree routines
• insert () insert a node into the tree
• treeHeight () - calculate the tree height
• inorder_traversals ()
• why do we need this?

class MyTree MyTree() public int
treeHeight(Node t) public int max(int a, int
b) public void computeNodePositions()
public void inorder_traversal(Node t, int
depth) public Node insert(Node root, String
s) // Binary Search tree insert
Explain the code
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Displaying the tree
ys
SCREENHEIGHT
SCREENWIDTH
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Algorithm

• Read data from text file r f g t h y b v c
• Insert each element into the binary tree
• Compute node positions (using inorder traversal
  and height information)
• JPanel displays the string that we input
• JPanel draws the filled Tree
• drawTree()

Explain the code
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HW1 Solutions