二叉树的前，中，后序遍历

public class BinaryTree {

    public static void main(String[] args) {
        Binary  binary = new Binary();
        Hero root = new Hero(1,"1");
        Hero hero2 = new Hero(2, "2");
        Hero hero3 = new Hero(3, "3");
        Hero hero4 = new Hero(4, "4");
        root.setLeft(hero2);
        root.setRight(hero3);
        hero3.setRight(hero4);
        binary.setRoot(root);
        //前序遍历
        System.out.println("前序遍历");
        binary.pre();
        //中序遍历
        System.out.println("中序遍历");
        binary.infix();
        //后序遍历
        System.out.println("后序遍历");
        binary.last();
    }
}

class Binary{
    private Hero root;
    
    public Hero getRoot() {
        return root;
    }
    public void setRoot(Hero root) {
        this.root = root;
    }
    //前序遍历
    public void pre() {
        if(root!=null) {
            root.pre();
        }else {
            System.out.println("二叉树为空,无法遍历");
        }
    }
    //中序遍历
    public void infix() {
        if(root!=null) {
            root.infix();
        }else {
            System.out.println("二叉树为空,无法遍历");
        }
    }
    //后序遍历
    public void last() {
        if(root!=null) {
            root.last();
        }else {
            System.out.println("二叉树为空,无法遍历");
        }
    }
}

class Hero{
    private int no;
    private String name;
    private Hero left;
    private Hero right;
    
    public Hero(int no,String name) {
        this.no = no;
        this.name = name;
    }
    public int getNo() {
        return no;
    }
    public void setNo(int no) {
        this.no = no;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Hero getLeft() {
        return left;
    }
    public void setLeft(Hero left) {
        this.left = left;
    }
    public Hero getRight() {
        return right;
    }
    public void setRight(Hero right) {
        this.right = right;
    }
    @Override
    public String toString() {
        return "Hero [no=" + no + ", name=" + name + "]";
    }
    
    public void pre() {
        System.out.println(this);
        if(this.left!=null) {
            this.left.pre();
        }
        if(this.right!=null) {
            this.right.pre();
        }
    }
    
    public void infix() {
        if(this.left!=null) {
            this.left.infix();
        }
        System.out.println(this);
        if(this.right!=null) {
            this.right.infix();
        }
    }
    
    public void last() {
        if(this.left!=null) {
            this.left.last();
        }
        if(this.right!=null) {
            this.right.last();
        }
        System.out.println(this);
    }
    
}