Java基础入门-2020-IDEA版-通俗易懂--零基础入门必备-三更草堂-笔记2

目录流程控制语句-if流程控制语句-switch循环语句-for循环语句-while循环语句-do...while循环控制语句循环相关练习Random生成随机数流程控制语句-if练习一package demo; public class demo1 { public static void main(String[] args) { int a 10; int b 20; int c 30; if (a5){ System.out.println(1); } else if (b6) { System.out.println(2); } else if (b7) { System.out.println(3); }else { System.out.println(4); } System.out.println(end); } }package demo; import java.util.Scanner; public class demo3 { public static void main(String[] args) { Scanner sc new Scanner(System.in); System.out.println(请输入你的语文成绩); int chinese sc.nextInt(); System.out.println(请输入你的英语成绩); int english sc.nextInt(); System.out.println(请输入你的数学成绩); int math sc.nextInt(); int sum chineseenglishmath; if (sum180){ System.out.println(由于您的优秀我想和你家长聊聊); } } }package demo; import java.util.Scanner; public class demo3 { public static void main(String[] args) { Scanner sc new Scanner(System.in); System.out.println(请输入你的语文成绩); int chinese sc.nextInt(); System.out.println(请输入你的英语成绩); int english sc.nextInt(); System.out.println(请输入你的数学成绩); int math sc.nextInt(); int sum chineseenglishmath; if (sum180){ System.out.println(叫家长); } else if (chinese98english98math98) { System.out.println(恭喜升任五道杠大队长); }else if (chinese95english95math95) { System.out.println(恭喜升任五道杠大队长); }else { System.out.println(同九义何汝秀); } } }流程控制语句-switchpackage demo; public class demo4 { public static void main(String[] args) { int num 3; switch (num){ case 1: System.out.println(1); break; case 2: System.out.println(2); break; case 3: System.out.println(3); break; default: System.out.println(default); break; } } }package demo; import java.util.Scanner; public class demo5 { public static void main(String[] args) { Scanner sc new Scanner(System.in); System.out.println(请输入0-6之间的整数); int num sc.nextInt(); switch(num){ case 0: System.out.println(星期日); break; case 1: System.out.println(星期一); break; case 2: System.out.println(星期二); break; case 3: System.out.println(星期三); break; case 4: System.out.println(星期四); break; case 5: System.out.println(星期五); break; case 6: System.out.println(星期六); break; default: System.out.println(请输入0-6的整数); break; } } }package demo; import java.util.Scanner; public class demo5 { public static void main(String[] args) { Scanner sc new Scanner(System.in); System.out.println(请输入一个月份); int mouth sc.nextInt(); switch(mouth){ case 3: case 4: case 5: System.out.println(春季); break; case 6: case 7: case 8: System.out.println(夏季); break; case 9: case 10: case 11: System.out.println(秋季); break; case 1: case 2: case 12: System.out.println(冬季); break; default: System.out.println(请输入1-12之间的数); break; } } }循环语句-forpackage demo; public class demo6 { public static void main(String[] args) { for (int i 1;i1315;i){ System.out.println(Hello World); } for (int i 1;i5;i){ System.out.println(i); } } }package demo; public class demo7 { //// 输出1到100所有的数 public static void main(String[] args) { // for (int i 1;i100;i){ // System.out.println(i); // } //// 输出100-1所有的数 // for (int i 100;i1;i--){ // System.out.println(i); // } // 要求输出1到100的和 int sum 0; for (int i 1;i100;i){ sumi; } System.out.println(sum); // 求1到100的偶数和 int sum1 0; for (int i 2;i100;i2){ sum1 i; } System.out.println(sum1); // 求1-100中可以被3整除又能被5整除的数有多少个 int count 0; for (int i 1;i100;i){ if (i%30i%50){ count; } } System.out.println(count); } }循环语句-whilepackage demo; import java.util.Scanner; public class demo8 { public static void main(String[] args) { // 让用户输入一个数字如果不是-1就让用户一直输入如果该数字为-1就结束循环 int num 0; Scanner sc new Scanner(System.in); while (num!-1){ System.out.println(请输入一个数字); num sc.nextInt(); } } }循环语句-do...whilepackage demo; import java.util.Scanner; public class demo9 { public static void main(String[] args) { //让用户输入一个数字如果不是-1就让用户一直输入如果该数字为-1就结束循环 int num; Scanner sc new Scanner(System.in); do{ System.out.println(请输入一个数字); num sc.nextInt(); }while(num!-1); } }循环控制语句循环相关练习package demo; public class demo10 { public static void main(String[] args) { // 获取10-99的总和与偶数的个数并且在控制台打印输出 int sum 0; int count 0; for (int i 10;i99;i){ sum i; if (i%20){ count 1; } } System.out.println(偶数个数count); System.out.println(总和:sum); } }package demo; public class demo11 { public static void main(String[] args) { double h 0.01; int count 0; while (h8848){ h h*2; count; } System.out.println(折叠的次数count); } }package demo; import java.util.Scanner; public class demo12 { public static void main(String[] args) { int result 1; for(int i 1;i8;i){ result * i; } System.out.println(result); } }package demo; public class demo13 { public static void main(String[] args) { int line 3; for(int i 1;iline;i){ for (int j 1;jline-i;j){ System.out.print( ); } for (int k 1;k2*i-1;k){ System.out.print(*); } System.out.println(); } } }package demo; public class demo14 { public static void main(String[] args) { for (int i 1;i9;i){ for (int j 1;ji;j){ System.out.print(j*ii*j); System.out.print(\t); } System.out.println(); } } }Random生成随机数package demo; import java.util.Random; public class RandoDemo { public static void main(String[] args) { Random r new Random(); int num r.nextInt(10)1; System.out.println(num); } }