创建二叉树类

public class tree {
    int data;
    tree left;
    tree right;
    public tree(int data, tree left, tree right) {
        super();
        this.data = data;
        this.left = left;
        this.right = right;
    }
    public tree(int data) {
        this.data=data;
        this.left=null;
        this.right=null;
    }
    public void  insert(tree t,int data){
        if(data>this.data){
            if(t.right==null){
                t.right=new tree(data);
            }else{
                t.insert(right,data);
            }
        }else if(data<=this.data){
            if(t.left==null){
                t.left=new tree(data);
            }else{
                t.insert(left,data);
            }
        }
    }
    
}

遍历二叉树

public class BinaryTree {
;
    public static void main(String[] args) {
        int [] arr ={21,33,44,23,56,79,456,32,98,7,5};
        tree root = new tree(arr[0]);
        for (int i = 1; i < arr.length; i++) {
            root.insert(root,arr[i]);
        }
        preOrder(root);
    }
    public static void  preOrder(tree root){
        if(root!=null){
            System.out.print(root.data+"-");
            preOrder(root.left);
            preOrder(root.right);
        }
        //System.out.println("先根遍历");
    }
    

}