More on Trees CS1316: Representing Structure and Behavior

More on Trees

CS1316: Representing Structure and Behavior

Story

Tree data structure as a list of lists

Visualizing trees

Traversing trees• Pre-order and post-order

Our SoundTree Class Structureabstract CollectableNode

Knows next

Knows How to do basic list operations, and defines abstract sound operations (can collect() its sound(s))

SoundBranch

Knows children

Knows How add children, and collect all the sounds from its children and next

SoundNode

Knows mySound

Knows How collect itself and its next

The subclasses extend CollectableNode

Our SoundTree Class Structure (a little further)

abstract CollectableNode

Knows next

Knows How to do basic list operations, and collect()

SoundBranch

Knows children

Knows How add children, and collect()

SoundNode

Knows mySound

Knows How collect()

ScaleBranch

Knows a scaling factor

Knows How to access scaling factor, and to collect from children then scale the resultant sound

Recall for handling sounds

Welcome to DrJava.> SoundTreeExample tree = new

SoundTreeExample(); tree.setUp();

> tree.play()

> tree.playScaled(2.0);

> tree.play();

What a tree “looks like” (printed, e.g., toString())> tree

SoundTreeExample@92b1a1

> tree.root()

SoundBranch (with child: SoundBranch (with child: SoundNode (with sound: Sound number of samples: 28568 and next: SoundNode (with sound: Sound number of samples: 46034 and next: null and next: ScaleBranch (1.0) SoundBranch (with child: SoundNode (with sound: Sound number of samples: 47392 and next: SoundNode (with sound: Sound number of samples: 32126 and next: null and next: SoundBranch (with child: SoundNode (with sound: Sound number of samples: 8452 and next: SoundNode (with sound: Sound number of samples: 28568 and next: null and next: No next))) and next: No next)

Obviously, this doesn’t help us much, but the root() does

But this textual representation isn’t so clear, is it? Could you modify toString() to fix this?

A visual alternative (hierarchical)

root: SoundBranch

branch1: SoundBranch

scaledBranch: ScaleBranch


SoundNode (clap+rest+snap)

SoundNode (aah+snap+rest)

SoundNode (clink+clave+gong)

SoundNode (is+chirp+clap)

SoundNode (clap+snap+snap)

SoundNode (bassoon+snap+clap)

Children of root

root: SoundBranch










A linked list, with branch1 as top/head of list.

If you look at the code, the variable children just points to the first child, which is the head of a linked list.

Children of branch1

root: SoundBranch










Also a linked list.

We are representing a tree as a list of lists.

Traversing the tree: tree.root().collect()

root: SoundBranch










public Sound collect(){ Sound childSound; if (children != null) {childSound = children.collect();} else {childSound = new Sound(1);}

SoundBranch code


root: SoundBranch










public Sound collect(){ Sound childSound; if (children != null) {childSound = children.collect();} else {childSound = new Sound(1);}

SoundBranch code


root: SoundBranch










SoundNode code

public Sound collect(){ if (this.getNext() == null) {return mySound;} else {return mySound.append(this.getNext().collect());} }


root: SoundBranch










SoundNode code

public Sound collect(){ if (this.getNext() == null) {return mySound;} else {return mySound.append(this.getNext().collect());} }

root: SoundBranch










Documents

More on Trees CS1316: Representing Structure and Behavior