Java 打印模板大全

• Java 打印模板下面这份够覆盖刷题和面试里大多数场景。import java.util.*;public class PrintTemplates {// 链表节点static class ListNode {int val;ListNode next;ListNode(int val) { this.val val; }}// 二叉树节点static class TreeNode {int val;TreeNode left, right;TreeNode(int val) { this.val val; }}// 自定义对象static class User {String name;int age;User(String name, int age) {this.name name;this.age age;}Overridepublic String toString() {return User{name name , age age };}}public static void main(String[] args) {// 1. 基本类型 / 字符串int x 10;String s hello;System.out.println(x);System.out.println(s);// 2. 一维数组int[] arr {1, 2, 3, 4};System.out.println(Arrays.toString(arr));// 3. 二维数组int[][] matrix {{1, 2}, {3, 4}, {5, 6}};System.out.println(Arrays.deepToString(matrix));// 4. 一行一行打印二维数组for (int[] row : matrix) {System.out.println(Arrays.toString(row));}// 5. ListListInteger list Arrays.asList(1, 2, 3);System.out.println(list);// 6. SetSetString set new HashSet(Arrays.asList(a, b, c));System.out.println(set);// 7. MapMapString, Integer map new HashMap();map.put(Alice, 18);map.put(Bob, 20);System.out.println(map);// 8. 自定义对象User user new User(Tom, 22);System.out.println(user);// 9. 对象数组 / 对象集合User[] users {new User(A, 10), new User(B, 20)};System.out.println(Arrays.toString(users));System.out.println(Arrays.asList(users));// 10. 链表ListNode head new ListNode(1);head.next new ListNode(2);head.next.next new ListNode(3);printList(head);// 11. 二叉树TreeNode root new TreeNode(1);root.left new TreeNode(2);root.right new TreeNode(3);root.left.right new TreeNode(4);System.out.print(前序: );preorder(root);System.out.println();System.out.print(中序: );inorder(root);System.out.println();System.out.print(后序: );postorder(root);System.out.println();System.out.print(层序: );levelOrder(root);System.out.println();// 12. 格式化输出System.out.printf(name%s, age%d%n, Jerry, 18);}// 打印链表public static void printList(ListNode head) {while (head ! null) {System.out.print(head.val);if (head.next ! null) {System.out.print( - );}head head.next;}System.out.println();}// 前序遍历public static void preorder(TreeNode root) {if (root null) return;System.out.print(root.val );preorder(root.left);preorder(root.right);}// 中序遍历public static void inorder(TreeNode root) {if (root null) return;inorder(root.left);System.out.print(root.val );inorder(root.right);}// 后序遍历public static void postorder(TreeNode root) {postorder(root.right);System.out.print(root.val );}// 层序遍历public static void levelOrder(TreeNode root) {if (root null) return;QueueTreeNode queue new LinkedList();queue.offer(root);while (!queue.isEmpty()) {TreeNode node queue.poll();System.out.print(node.val );if (node.left ! null) queue.offer(node.left);if (node.right ! null) queue.offer(node.right);}}}最常用速记版- 一维数组Arrays.toString(arr)- 二维数组Arrays.deepToString(arr)- 集合System.out.println(list)- MapSystem.out.println(map)- 链表while 遍历打印- 二叉树前序 / 中序 / 后序 / 层序- 自定义对象重写 toString()补充如果你刷 LeetCode最实用的是这几个System.out.println(Arrays.toString(arr));System.out.println(Arrays.deepToString(matrix));System.out.println(list);System.out.println(map);printList(head);levelOrder(root);