Java二叉树前中后序遍历，前中后序查找，删除结点

结点二叉树
前序遍历，中序遍历，后序遍历
前序查找，中序查找，后序查找
删除结点

public class BiraryTreeDemo {
    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);
        TreeNode node2 = new TreeNode(2);
        TreeNode node3 = new TreeNode(3);
        TreeNode node4 = new TreeNode(4);
        TreeNode node5 = new TreeNode(5);
        root.setLeft(node2);
        root.setRight(node3);
        node3.setLeft(node5);
        node3.setRight(node4);
        BinaryTree binaryTree = new BinaryTree();
        //设置根节点
        binaryTree.setRoot(root);
//        System.out.println("前序遍历");
//        binaryTree.preOrder();
//        System.out.println("中序遍历");
//        binaryTree.infixOrder();
//        System.out.println("后序遍历");
//        binaryTree.postOrder();

//        System.out.println("前序遍历查找");
//        TreeNode treeNode = 			binaryTree.postOrderSearch(15);
//
//        if (treeNode != null) {
//            System.out.println(treeNode);
//        }
        System.out.println("删除前，前序遍历");
        binaryTree.postOrder();
        System.out.println("删除后，前序遍历");
        binaryTree.deleteNode(3);
        binaryTree.postOrder();
        
    }
}

class BinaryTree {
    private TreeNode root;

    public void setRoot(TreeNode root) {
        this.root = root;
    }

    //前序遍历
    public void preOrder() {
        if (this.root != null) {
            this.root.preOrder();
        } else {
            System.out.println("二叉树为空");
        }
    }

    public void infixOrder() {
        if (this.root != null) {
            this.root.infixOrder();
        } else {
            System.out.println("二叉树为空");
        }

    }

    public void postOrder() {
        if (this.root != null) {
            this.root.postOrder();
        } else {
            System.out.println("二叉树为空");
        }


    }

    public TreeNode preOrderSearch(int no) {
        if (root != null) {
            return root.preOrderSearch(no);
        } else {
            return null;
        }
    }

    public TreeNode infixOrderSearch(int no) {
        if (root != null) {
            return root.infixOrderSearch(no);
        } else {
            return null;
        }
    }

    public TreeNode postOrderSearch(int no) {
        if (root != null) {
            return root.postOrderSearch(no);
        } else {
            return null;
        }
    }

    public void deleteNode(int no) {
        if (root != null) {
            //判断根节点是否为要删除的
            if (root.getVal() == no) {
                root = null;
            } else {
                root.deleteNode(no);
            }
        } else {
            System.out.println("二叉树为空");
        }
    }


}


class TreeNode {
    private int val;
    private TreeNode left;
    private TreeNode right;

    public TreeNode(int val) {
        this.val = val;
    }

    public int getVal() {
        return val;
    }

    public void setVal(int val) {
        this.val = val;
    }

    public TreeNode getLeft() {
        return left;
    }

    public void setLeft(TreeNode left) {
        this.left = left;
    }

    public TreeNode getRight() {
        return right;
    }

    public void setRight(TreeNode right) {
        this.right = right;
    }

    @Override
    public String toString() {
        return "TreeNode{" +
                "val=" + val +
                '}';
    }

    //前序遍历方法
    public void preOrder() {
        //先输出父结点
        System.out.println(this);
        //递归左子树
        if (this.left != null) {
            this.left.preOrder();
        }
        if (this.right != null) {
            this.right.preOrder();
        }
    }

    //中序遍历
    public void infixOrder() {
        //
        if (this.left != null) {
            this.left.infixOrder();
        }
        System.out.println(this);
        if (this.right != null) {
            this.right.infixOrder();
        }
    }

    public void postOrder() {
        if (this.left != null) {
            this.left.postOrder();
        }
        if (this.right != null) {
            this.right.postOrder();
        }
        System.out.println(this);

    }

    /**
     * @param no 查找的no
     * @return 返回结点
     **/
    public TreeNode preOrderSearch(int no) {
        System.out.println("进入前序遍历查找");
        if (this.val == no) {
            return this;
        }
        TreeNode trs = null;
        if (this.left != null) {
            trs = this.left.preOrderSearch(no);
        }
        //说明左子树找到了
        if (trs != null) {
            return trs;
        }
        //左子树没找到，找右子树
        if (this.right != null) {
            trs = this.right.preOrderSearch(no);
        }
        return trs;
    }

    public TreeNode infixOrderSearch(int no) {
        TreeNode trs = null;
        if (this.left != null) {
            trs = this.left.infixOrderSearch(no);

        }
        if (trs != null) {
            return trs;
        }
        System.out.println("进入中序遍历查找");
        if (this.val == no) {
            return this;
        }
        if (this.right != null) {
            trs = this.right.infixOrderSearch(no);
        }
        return trs;
    }

    public TreeNode postOrderSearch(int no) {
        TreeNode trs = null;
        if (this.left != null) {
            trs = this.left.postOrderSearch(no);
        }
        if (trs != null) {
            return trs;
        }
        if (this.right != null) {
            trs = this.right.postOrderSearch(no);
        }
        if (trs != null) {
            return trs;
        }
        System.out.println("进入后序遍历查找");
        if (this.val == no) {
            return this;
        }
        return trs;
    }

    //递归删除结点
    public void deleteNode(int no) {
        if (this.left != null && this.left.val == no) {
            this.left = null;
            return;
        }
        if (this.right != null && this.right.val == no) {
            this.right = null;
            return;
        }
        if (this.left != null) {
            this.left.deleteNode(no);
        }
        if (this.right != null) {
            this.right.deleteNode(no);
        }

    }


}