java实现二叉树

public class Node {
public int value;
public Node left;
public Node right;

public void store(int value)
{
if(value<this.value)
{
if(left == null)
{
left = new Node();
left.value=value;
}
else
{
left.store(value);
}
}
else if(value>this.value)
{
if(right == null)
{
right = new Node();
right.value=value;
}
else
{
right.store(value);
}
}
}

public boolean find(int value)
{
System.out.println("happen " + this.value);
if(value == this.value)
{
return true;
}
else if(value>this.value)
{
if(right == null) return false;
return right.find(value);
}else
{
if(left == null) return false;
return left.find(value);
}

}

public  void preList()
{
System.out.print(this.value + ",");
if(left!=null) left.preList();
if(right!=null) right.preList();
}

public void middleList()
{
if(left!=null) left.preList();
System.out.print(this.value + ",");
if(right!=null) right.preList();
}
public void afterList()
{
if(left!=null) left.preList();
if(right!=null) right.preList();
System.out.print(this.value + ",");
}
public static void main(String [] args)
{
int [] data = new int[20];
for(int i=0;i<data.length;i++)
{
data[i] = (int)(Math.random()*100) + 1;
System.out.print(data[i] + ",");
}
System.out.println();

Node root = new Node();
root.value = data[0];
for(int i=1;i<data.length;i++)
{
root.store(data[i]);
}

root.find(data[19]);

root.preList();
System.out.println();
root.middleList();
System.out.println();
root.afterList();
}
}