一，定义一个节点类：
package test;
public class Node {
private int data;
private Node left;
private Node right;
public Node(int data) {
this.data = data;
}
public int getData() {
return data;
}
public void setData(int data) {
this.data = data;
}
public Node getLeft() {
return left;
}
public void setLeft(Node left) {
this.left = left;
}
public Node getRight() {
return right;
}
public void setRight(Node right) {
this.right = right;
}
}
二，定义一个算法实现类：
package test;
public class FindTree {
private void visit(int data) {
System.out.print(data+"--");
}
public void preOrder(Node root) {
if(root == null) {
return;
}
visit(root.getData());
preOrder(root.getLeft());
preOrder(root.getRight());
}
public void inOrder(Node root) {
if(root == null) {
return;
}
inOrder(root.getLeft());
visit(root.getData());
inOrder(root.getRight());
}
public void afterOrder(Node root) {
if(root == null) {
return;
}
afterOrder(root.getLeft());
afterOrder(root.getRight());
visit(root.getData());
}
}
三，构建一个二叉树
package test;
public class TestTree {
public static void main(String[] args) {
FindTree ft = new FindTree();
int[] array = {12,76,35,22,16,48,90,46,9,40};
int j = 0;
Node root = new Node(array[j]);
for(int i = 1; i< array.length; i++) {
insert(root, array[i]);
}
System.out.println("preorder----------------------------------");
ft.preOrder(root);
System.out.println("
inorder----------------------------------");
ft.inOrder(root);
System.out.println("
afterorder----------------------------------");
ft.afterOrder(root);
}
private static void insert(Node root, int data) {
//二叉树中左边的孩子节点小于父节点，右边的孩子节点大于父节点
if(root.getData() < data) {
if(root.getRight() == null) {
root.setRight(new Node(data));
} else {
insert(root.getRight(), data);
}
} else {
if(root.getLeft() == null) {
root.setLeft(new Node(data));
} else {
insert(root.getLeft(), data);
}
}
}
}
四，打印结果：
preorder----------------------------------
12--9--76--35--22--16--48--46--40--90--
inorder----------------------------------
9--12--16--22--35--40--46--48--76--90--
afterorder----------------------------------
9--16--22--40--46--48--35--90--76--12--