【连载】Java学习系列（004）——程序逻辑-2（分支和循环）

Java基础

第四天：程序逻辑-2（分支和循环）

练习1：猜数字（人猜/机器猜）

package com.lovoinfo;import java.util.Scanner;/*** 猜数字* @author jackfrued**/
public class Test04 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int correctAnswer = (int) (Math.random() * 100 + 1);int counter = 0;int thyAnswer;do {System.out.print("请输入你猜的数字: ");thyAnswer = sc.nextInt();counter += 1;if (thyAnswer == correctAnswer) {System.out.println("恭喜你猜对了!总共猜了" + counter + "次");if(counter > 7) {System.out.println("智商拙计!!!");}} else if (thyAnswer > correctAnswer) {System.out.println("小一点!");} else {System.out.println("大一点");}} while (thyAnswer != correctAnswer);sc.close();}
}

练习2：人机猜拳

package com.lovoinfo;import java.util.Scanner;/*** 人机猜拳* @author jackfrued**/
public class Test05 {/*** 将出拳对应的数字变成中文* @param fist 出拳的数字* @return 出拳字对应的中文*/public static String getFist(int fist) {String str;if(fist == 1) {str = "剪刀";}else if(fist == 2) {str = "石头";}else {str = "布";}return str;}public static void main(String[] args) {Scanner sc = new Scanner(System.in);int money = 1000;do {int debt;do {System.out.println("你总共有" + money + "元");System.out.print("请下注: ");debt = sc.nextInt();} while(debt <= 0 || debt > money);int computerFist = (int) (Math.random() * 3 + 1);int thyFist;do {System.out.print("请出拳(1. 剪刀; 2. 石头; 3. 布): ");thyFist = sc.nextInt();} while (thyFist < 1 || thyFist > 3);System.out.println("计算机出的是" + getFist(computerFist));System.out.println("你出的是" + getFist(thyFist));if(computerFist == thyFist) {System.out.println("平局!");}else {if(computerFist == 1) {if(thyFist == 2) {money += debt;System.out.println("你赢了!");}else {money -= debt;System.out.println("计算机赢了!");}}else if(computerFist == 2) {if(thyFist == 1) {money -= debt;System.out.println("计算机赢了!");}else {money += debt;System.out.println("你赢了!");}}else {if(thyFist == 1) {money += debt;System.out.println("你赢了!");}else {money -= debt;System.out.println("计算机赢了!");}}}} while(money > 0);System.out.println("你破产了!游戏结束!");sc.close();}
}

练习3：Craps赌博游戏

package com.lovoinfo;import java.util.Scanner;/*** Craps赌博游戏* @author jackfrued**/
public class Test03 {/*** 摇两颗色子* @return 两个色子摇出的点数之和*/public static int rollDice() {int face1 = (int) (Math.random() * 6 + 1);int face2 = (int) (Math.random() * 6 + 1);return face1 + face2;}public static void main(String[] args) {Scanner sc = new Scanner(System.in);int money = 1000;do {int debt = 0;   // 下注的金额do {System.out.println("你的余额" + money + "元");System.out.print("请下注: ");if(sc.hasNextInt()) {   // 判断能否读到一个整数debt = sc.nextInt();}else {System.out.println("输入错误!");sc.nextLine();  // 把错误的输入读走}} while (debt <= 0 || debt > money);int firstPoint = rollDice();System.out.println("玩家摇出了" + firstPoint + "点");boolean gameOver = true;    // 表示游戏是否应该结束的布尔值switch(firstPoint) {case 7:case 11:money += debt;System.out.println("玩家胜!");break;case 2:case 3:case 12:money -= debt;System.out.println("庄家胜!");break;default:gameOver = false;   // 如果第一次没有分出胜负游戏就没有结束}while(!gameOver) {  // 只要游戏没有结束就要继续摇色子int currentPoint = rollDice();System.out.println("玩家摇出了" + currentPoint + "点");if(currentPoint == 7) {money -= debt;System.out.println("庄家胜!");gameOver = true;}else if(currentPoint == firstPoint) {money += debt;System.out.println("玩家胜!");gameOver = true;}}} while(money > 0);System.out.println("恭喜你, 破产了!");sc.close();}
}

练习4：九九表

package com.lovoinfo;public class Test09 {public static void main(String[] args) {for(int i = 1; i <= 9; i++) {for(int j = 1; j <= i; j++) {System.out.printf("%d*%d=%d\t", i, j, i * j);}System.out.println();}}}

作业：输出直角三角形图案。

package com.lovoinfo;public class Test10 {private static final int ROW = 10;public static void main(String[] args) {for(int i = 1; i <= ROW; i++) {for(int j = 1; j <= i; j++) {System.out.print("*");}System.out.println();}System.out.println("\n---华丽的分隔线---\n");for(int i = 1; i <= ROW; i++) {for(int j = ROW; j >= i; j--) {System.out.print("*");}System.out.println();}System.out.println("\n---华丽的分隔线---\n");for(int i = 1; i <= ROW; i++) {for(int j = 1; j <= ROW; j++) {if((ROW - i) >= j) {System.out.print(" ");}else {System.out.print("*");}}System.out.println();}}}

练习5：百钱百鸡

package com.lovoinfo;/*** 百钱买百鸡(穷举法)* @author jackfrued**/public class Test14 {public static void main(String[] args) {System.out.println("公鸡\t母鸡\t小鸡");// 假设公鸡x只, 母鸡y只, 小鸡z只for(int x = 0; x <= 20; x++) {for(int y = 0; y <= 33; y++) {int z = 100 - x - y;if(5 * x + 3 * y + z / 3 == 100 && z % 3 == 0) {System.out.printf("%d\t%d\t%d\n", x, y, z);}}}}}

作业：21根火柴游戏。
桌上有21根火柴，人和计算机轮流拿火柴，每次最少1根，最多4根，谁拿到最后一根火柴谁就输了。编程模拟此游戏，每次都由人先拿，并保证计算机一定能够获得胜利。

package cn.laibin;import java.util.Scanner;public class AssignMatch {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int human = 0;int computer = 0;int total = 21;do {System.out.printf("还剩  %d 支火柴！\n", total);System.out.print("你拿走（1-4支）：");human = sc.nextInt();computer = 5 - human;   //计算机拿走5-human，使得最后总会剩下一支火柴让human拿，以保证计算机获胜System.out.printf("计算机拿走  %d 支火柴！\n", computer);total -= 5;} while (total > 1);System.out.println("只剩下一根火柴了，你输了！");sc.close();}
}

Java基础思维导图