Java學(xué)習(xí)筆記 - 第004天

分支結(jié)構(gòu)

分支結(jié)構(gòu)(選擇結(jié)構(gòu)) - switch 開(kāi)關(guān)
case 不加 break 就會(huì)一直往下執(zhí)行囚霸，default 不用(因?yàn)槭亲詈笠粋€(gè))
x可以用整數(shù)、字符激才、枚舉邮辽、字符串，只能做等值判斷
switch (x)

例子

1. 輸入1-12的數(shù)字代表月份輸出對(duì)應(yīng)的英文單詞

        Scanner input = new Scanner(System.in);
        System.out.print("請(qǐng)輸入月份: ");
        int month = input.nextInt();
        String wordOfMonth;
        // switch - 開(kāi)關(guān)
        // case 不加 break 就會(huì)一直往下執(zhí)行贸营，default 不用(因?yàn)槭亲詈笠粋€(gè))
        // 整數(shù)吨述、字符、枚舉钞脂、字符串 只能做等值判斷
        switch (month) {
        case 1: wordOfMonth = "January"; break;
        case 2: wordOfMonth = "February"; break; 
        case 3: wordOfMonth = "March"; break;
        case 4: wordOfMonth = "April"; break;
        case 5: wordOfMonth = "May"; break;
        case 6: wordOfMonth = "June"; break;
        case 7: wordOfMonth = "July"; break;
        case 8: wordOfMonth = "August"; break;
        case 9: wordOfMonth = "September"; break;
        case 10: wordOfMonth = "October"; break;
        case 11: wordOfMonth = "November"; break;
        case 12: wordOfMonth = "December"; break;
        default: wordOfMonth = "輸出錯(cuò)誤";
        }
        System.out.println(wordOfMonth);
        input.close();

2. 自動(dòng)問(wèn)答機(jī)器人

        Scanner input = new Scanner(System.in);
        System.out.print("請(qǐng)輸入: ");
        String yourQuestion = input.nextLine();
        String answer;
        switch (yourQuestion) {
        case "你好":
            answer = "你好啊";
            break;
        case "今天天氣怎么樣":
            answer = "你自己去看天氣預(yù)報(bào)";
            break;
        case "操你大爺":
        case "滾蛋":
            answer = "請(qǐng)文明用語(yǔ)";
            break;
        default:
            answer = "聽(tīng)不懂";
            break;
        }
        System.out.println("計(jì)算機(jī)說(shuō): " + answer);
        input.close();

練習(xí)

1.搖骰子決定懲罰方式

//random() -  [0,1)
        int face = (int) (Math.random() * 6 + 1);
        System.out.println("搖出了 " + face + "點(diǎn)" );
        String punishment = "";
        switch (face) { 
        case 1:
            punishment = "喝酒";
            break;
        case 2:
            punishment = "唱歌";
            break;
        case 3:
            punishment = "真心話";
            break;
        case 4:
            punishment = "大冒險(xiǎn)";
            break;
        case 5:
            punishment = "脫衣服";
            break;
        case 6:
            punishment = "給錢";
            break;
        /*
         * 方法二:
         * String punishment;
         default:
            punishment = "給錢";
            break;
         */
        }
        System.out.println("你的懲罰是: " + punishment);

循環(huán)結(jié)構(gòu)

while 循環(huán)

        int i = 1;
        while (i <= 10) {
            System.out.println(i + ". Hello World!");
            i += 1;
        }
        System.out.println("循環(huán)結(jié)束揣云！");

do-while 循環(huán)

        int i = 0;
        do {
            System.out.println(i + ". Hello World!");
            i += 1;
        } while (i < 10);

for 循環(huán) ①; ②;③
①: 初始條件，只在第一次進(jìn)循環(huán)執(zhí)行一次冰啃，以后不會(huì)執(zhí)行
②: 循環(huán)條件
③: 循環(huán)體最后一條語(yǔ)句邓夕，每循環(huán)一次執(zhí)行一次

        for (int i = 1; i <= 10; i++) {
            System.out.println(i + ". Hello World!");           
        }
        System.out.println("循環(huán)結(jié)束！");

例子

1.1-100求和

/*      int sum = 0;
        int i = 1;
        while (i <= 100) {
            if (i % 5 == 0 || i % 3 == 0 || i % 7 == 0) {
                sum += i;
            }
            i += 1;
        }*/
    
         // while () ;   
         // while 管后面的 空語(yǔ)句     ;
     
 /*     int sum = 0;
        int i = 1;
        do {
            sum += i;
            i += 1;
        } while (i<=100);
        */
        
        int sum = 0;
        for (int i = 1; i <= 100; i++) {
            sum += i;
        }
        System.out.println(sum);

練習(xí)

1.計(jì)算機(jī)出一個(gè)1~100隨機(jī)數(shù)阎毅，猜計(jì)算機(jī)出的數(shù)是什么焚刚，猜大提示猜大了。扇调。矿咕。。猜對(duì)了提示猜對(duì)了，猜錯(cuò) 7次提示智商捉急

        int answer = (int) (Math.random() * 100 + 1);
        int i = 0;
        Scanner input = new Scanner(System.in);
        while (true) {
            System.out.print("猜下數(shù)字是多少： ");
            int num = input.nextInt();
            i += 1;
/*          if (i == 7) {
                System.out.println("你智商真捉急!");
            }*/
            if (num < answer) {
                System.out.println("猜小了!");
            }
            else if (num > answer) {
                System.out.println("猜大了!");
            }
            else {
                System.out.println("猜對(duì)了!");
                if (i <= 3) {
                    System.out.println("你真厲害!");
                }
                else if (i >= 7){
                    System.out.println("你智商真捉急!");
                }
                input.close();
                break;
            }
        }

修正后代碼:

        Scanner input = new Scanner(System.in);
        int answer = (int) (Math.random() * 100 + 1);
        int thyAnswer;
        int counter = 0;
        do {
            counter += 1;
            System.out.print("請(qǐng)輸入你猜的數(shù)字: ");
            thyAnswer = input.nextInt();
            if (thyAnswer > answer) {
                System.out.println("小一點(diǎn)!");
            }
            else if (thyAnswer < answer) {
                System.out.println("大一點(diǎn)!");
            }
            else {
                System.out.println("恭喜你答對(duì)了! 你總共猜了" + counter + "次.");
            }
        } while (thyAnswer != answer);
        
        if (counter > 7) {
            System.out.println("智商捉急!!!");
        }
        
        input.close();

2.n! = n * (n - 1) * (n - 2) ··· 3 * 2 * 1

/*      Scanner input =new Scanner(System.in);
        System.out.print("請(qǐng)輸入一個(gè)正整數(shù): ");
        int num = input.nextInt();
        int result = 1;
        for (int i = num; i >= 1; i--) {
            result *= i; 
        }
        System.out.println(num + "! = " + result);
        input.close();*/
        
        Scanner input = new Scanner(System.in);
        System.out.print("n = ");
        int n = input.nextInt();
        if (n >= 0) {
            double result = 1;
            for (int i = 2; i <= n; i++) {
                result *= i;
            }
            System.out.println(n + "! = " + result);
        }
        else {
            System.err.println("輸入錯(cuò)誤碳柱！");
        }
        input.close();

作業(yè)

1.把一顆骰子搖6W次捡絮，統(tǒng)計(jì)每一面出現(xiàn)的次數(shù)

        int face = 0;
        int oneSum = 0;
        int twoSum = 0;
        int threeSum = 0;
        int fourSum = 0;
        int fiveSum = 0;
        int sixSum = 0;
        for (int i = 0; i < 60000; i++) {
            face = (int) (Math.random() * 6 + 1);
            switch (face) {
            case 1:
                oneSum += 1;
                break;
            case 2:
                twoSum += 1;
                break;
            case 3:
                threeSum += 1;
                break;
            case 4:
                fourSum += 1;
                break;
            case 5:
                fiveSum += 1;
                break;
            case 6:
                sixSum += 1;
                break;
            }
        }
        System.out.printf("1 出現(xiàn)的次數(shù): %d,\n2 出現(xiàn)的次數(shù): %d,\n3 出現(xiàn)的次數(shù): %d,\n"
                + "4 出現(xiàn)的次數(shù): %d,\n5 出現(xiàn)的次數(shù): %d,\n6 出現(xiàn)的次數(shù): %d",oneSum,twoSum,threeSum,
                fourSum,fiveSum,sixSum);

修正后代碼:

        int f1 = 0, f2 = 0, f3 = 0, f4 = 0, f5 = 0, f6 = 0;
        // f1 = f2 = f3 = f4 = f5 = f6 = 0;
        for (int i = 0; i < 60000; i++) {
            int face = (int) (Math.random() * 6 + 1);
            switch (face) {
            case 1: f1 += 1; break;
            case 2: f2 += 1; break;
            case 3: f3 += 1; break;
            case 4: f4 += 1; break;
            case 5: f5 += 1; break;
            case 6: f6 += 1; break;
            }
        }
        System.out.println("1點(diǎn)搖出了 " + f1 + " 次");
        System.out.println("2點(diǎn)搖出了 " + f2 + " 次");
        System.out.println("3點(diǎn)搖出了 " + f3 + " 次");
        System.out.println("4點(diǎn)搖出了 " + f4 + " 次");
        System.out.println("5點(diǎn)搖出了 " + f5 + " 次");
        System.out.println("6點(diǎn)搖出了 " + f6 + " 次");

2.找出100 ~ 999之間水仙花數(shù) 153 = 1³⁺⁵3+3^3

        int bit = 0;
        int ten = 0;
        int hundreds = 0;
        int sum;
        for (int i = 100; i <= 999; i++) {
            bit = i % 10;
            ten = i / 10 % 10;
            hundreds = i / 100 ;
            sum = bit * bit * bit + ten * ten * ten + hundreds * hundreds * hundreds;
            if (i == sum) {
                System.out.println(i);
            }
        }

修正后代碼：

        for (int i = 100; i < 999; i++) {
            int bw = i / 100;
            int sw = i / 10 % 10;
            int gw = i % 10;
            if (i == bw * bw * bw + sw * sw * sw + gw * gw * gw) {
                System.out.println(i);
            }
        }

3.輸入兩個(gè)正整數(shù) 求最大公約數(shù)和最小公倍數(shù)

        Scanner input = new Scanner(System.in);
        System.out.print("輸入兩個(gè)正整數(shù): ");
        int a = input.nextInt();
        int b = input.nextInt();
        int min = a < b ? a : b;
        int max = a > b ? a : b;
        int greatestCommonDivisor = 0;
        int leastCommonMultiple = 0;
        for (int i = min; i >= 1; i--) {
            if (a % i == 0 && b % i == 0) {
                greatestCommonDivisor = i;
                break;
            }
        }
        for (int i = max; i < a * b; i++) {
            if (i % a == 0 && i % b == 0) {
                leastCommonMultiple = i;
                break;
            }
        }
        System.out.println(a + "和" + b  + "的最大公約數(shù)是:" + 
        greatestCommonDivisor + " ，最大公倍數(shù)是: " + leastCommonMultiple);
        input.close();

修正后代碼：

        Scanner input = new Scanner(System.in);
        System.out.print("請(qǐng)輸入兩個(gè)數(shù): ");
        int x = input.nextInt();
        int y = input.nextInt();
        for (int i = x < y ? x : y; i >= 1; i--) {
            if (x % i == 0 && y % i == 0) {
                System.out.println("最大公約數(shù): " + i);
                System.out.println("最小公倍數(shù): " + x * y / i);
                break; // 提前結(jié)束循環(huán)
            }
        }
        input.close();

晚作業(yè)

**1.Craps賭博游戲 - **
**兩顆色子 - **
**第一次: **
玩家搖出 7 和11 玩家勝
2 3 或12 莊家勝
其他點(diǎn)數(shù) 游戲繼續(xù)
玩家再搖
如果搖出7點(diǎn) 莊家勝
如果搖出了第一次的點(diǎn)數(shù) 玩家勝
其他情況游戲繼續(xù)
首次編寫(xiě)：

        int dealerMoney = 1000;
        int playerMoney = 1000;
        int face1 = (int) (Math.random() * 6 + 1);
        int face2 = (int) (Math.random() * 6 + 1);
        int count = face1 + face2;
        int time = 1;
        boolean victory = true;
        do {
            System.out.printf("游戲開(kāi)始: \n莊家的金錢 : %d 元,玩家的金錢 : %d 元\n",
                    dealerMoney,playerMoney);
            System.out.println("第"+ time +"次搖出" + count +"點(diǎn)");
            if (count == 7 || count == 11) {
                victory = false;
                System.out.println("玩家獲勝!");
            }
            else if(count == 2 || count == 3 || count == 12) {
                victory =false;
                System.out.println("莊家獲勝!");
            }
            else {
                do {
                    face1 = (int) (Math.random() * 6 + 1);
                    face2 = (int) (Math.random() * 6 + 1);
                    int count2 = face1 + face2;
                    time += 1;
                    System.out.println("第"+ time +"次搖出" + count2 +"點(diǎn)");
                    if (count2 == 7) {
                        victory = false;
                        System.out.println("莊家獲勝!");
                    }
                    else if (count2 == count) {
                        victory = false;
                        System.out.println("玩家獲勝!");
                    }
                } while (victory);
            }
        } while (victory);

第一次修改代碼:

        int dealerMoney = 1000;
        int playerMoney = 1000;
        
        boolean over = true;
        System.out.printf("游戲開(kāi)始: \n莊家的金錢 : %d 元,玩家的金錢 : %d 元\n",
                dealerMoney,playerMoney);
        do {
            int face1 = (int) (Math.random() * 6 + 1);
            int face2 = (int) (Math.random() * 6 + 1);
            int count = face1 + face2;
            int time = 1;
            
            System.out.println("第"+ time +"次搖出" + count +"點(diǎn)");
            if (count == 7 || count == 11) {
                System.out.println("玩家獲勝!");
                playerMoney += 100;
                dealerMoney -= 100;
            }
            else if(count == 2 || count == 3 || count == 12) {
                System.out.println("莊家獲勝!");
                playerMoney -= 100;
                dealerMoney += 100;
            }
            else {
                boolean victory = true;
                do {
                    face1 = (int) (Math.random() * 6 + 1);
                    face2 = (int) (Math.random() * 6 + 1);
                    int count2 = face1 + face2;
                    time += 1;
                    System.out.println("第"+ time +"次搖出" + count2 +"點(diǎn)");
                    if (count2 == 7) {
                        victory = false;
                        System.out.println("莊家獲勝!");
                        playerMoney -= 100;
                        dealerMoney += 100;
                    }
                    else if (count2 == count) {
                        victory = false;
                        System.out.println("玩家獲勝!");
                        playerMoney += 100;
                        dealerMoney -= 100;
                    }
                } while (victory);
            }
            System.out.printf("\n游戲現(xiàn)在: \n莊家的金錢 : %d 元,玩家的金錢 : %d 元\n",
                    dealerMoney,playerMoney);
            if(dealerMoney == 0 || playerMoney == 0){
                over = false;
                System.out.println("游戲結(jié)束");
            }
        } while (over);

第二次修改代碼：

        Scanner input = new Scanner(System.in);

        int dealerMoney = 1000;
        int playerMoney = 1000;
        
        boolean over = true;
        System.out.printf("游戲開(kāi)始: \n莊家的金錢 : %d 元,玩家的金錢 : %d 元\n",
                dealerMoney,playerMoney);
        do {
            int money;
            do {
                System.out.print("請(qǐng)下注: ");
                int inMoney = input.nextInt();
                if (playerMoney - inMoney > 0 && dealerMoney - inMoney > 0) {
                    money = inMoney;
                }
                else {
                    System.out.println("下注金額超出雙方某一方的剩余金額莲镣！");
                    money = 0;
                }
            } while (money == 0);
            
            int face1 = (int) (Math.random() * 6 + 1);
            int face2 = (int) (Math.random() * 6 + 1);
            int count = face1 + face2;
            int time = 1;
            
            System.out.println("第"+ time +"次搖出" + count +"點(diǎn)");
            if (count == 7 || count == 11) {
                System.out.println("玩家獲勝!");
                playerMoney += money;
                dealerMoney -= money;
            }
            else if(count == 2 || count == 3 || count == 12) {
                System.out.println("莊家獲勝!");
                playerMoney -= money;
                dealerMoney += money;
            }
            else {
                boolean victory = true;
                do {
                    face1 = (int) (Math.random() * 6 + 1);
                    face2 = (int) (Math.random() * 6 + 1);
                    int count2 = face1 + face2;
                    time += 1;
                    System.out.println("第"+ time +"次搖出" + count2 +"點(diǎn)");
                    if (count2 == 7) {
                        victory = false;
                        System.out.println("莊家獲勝!");
                        playerMoney -= money;
                        dealerMoney += money;
                    }
                    else if (count2 == count) {
                        victory = false;
                        System.out.println("玩家獲勝!");
                        playerMoney += money;
                        dealerMoney -= money;
                    }
                } while (victory);
            }
            System.out.printf("\n游戲現(xiàn)在: \n莊家的金錢 : %d 元,玩家的金錢 : %d 元\n",
                    dealerMoney,playerMoney);
            if(dealerMoney == 0 || playerMoney == 0){
                over = false;
                System.out.println("游戲結(jié)束");
            }
        } while (over);
        input.close();

最后編輯于：2017.12.04 21:26:11

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