java学习之路 之 基本语法-程序流程控制-（if-else)语句练习题

public class IfTest {public static void main(String[] args) {int a = 200;/*if (布尔表达式) {语句块 // 要想执行必须布尔表达式为真}*/if (a == 20) {System.out.println("a==20"); // 有条件地执行}System.out.println("after if...");}}class IfTest2 {public static void main(String[] args) {int a = 20;if (a == 200) {System.out.println("a==20");} else { // 否则, 如果if中的条件为假, 执行下面的语句System.out.println("else");}System.out.println("after if else ...");}}class IfTest3 {// 分支 : 多个条件, 只允许有一个执行public static void main(String[] args) {int a = 20;if (a == 10) {System.out.println("a==10");} else if (a == 20) {System.out.println("a==20");} else if (a == 30) {System.out.println("a==30");} else {System.out.println("else");}System.out.println("after if else if ...");}}class Exer3 {public static void main(String[] args) {/*从命令行参数接收小明的期末成绩。当成绩为100分时，奖励一辆BMW；当成绩为（80，99]时，奖励一个台iphone6s；if (80 < score <= 99)当成绩为[60,80]时，奖励一本参考书；其它时，什么奖励也没有。提示: 从命令行参数获取整数的代码:int score = Integer.parseInt(args[0]);*/int score = Integer.parseInt(args[0]);if (score > 100 || score < 0) {System.out.println("输入的数据非法");} else if (score == 100) {System.out.println("奖励一辆BMW");} else if (score > 80 && score <= 99) {System.out.println("奖励一个台iphone6s");} else if (score >= 60 && score <= 80) {System.out.println("奖励一本参考书");} else {System.out.println("什么奖励也没有");}}}/*大家都知道，男大当婚，女大当嫁。那么女方家长要嫁女儿，当然要提出一定的条件：高：180cm以上；富：财富1千万以上；帅：是。如果这三个条件同时满足，则：“我一定要嫁给他!!!”如果三个条件有为真的情况，则：“嫁吧，比上不足，比下有余。”如果三个条件都不满足，则：“不嫁！”*/public class IfTest {public static void main(String[] args) {int heigh = Integer.parseInt(args[0]);int money = Integer.parseInt(args[1]);boolean b = Boolean.parseBoolean(args[2]);if (heigh > 180 && money > 1000 && b == true) {System.out.println("我一定要嫁给他!!!");} else if (heigh > 180 || money > 1000 || b == true) {System.out.println("嫁吧，比上不足，比下有余");} else {System.out.println("不嫁！");}}}//编写程序：接收三个命令行字符串并转换为整数分别存入变量num1、num2、num3，对它们//进行排序(使用 if-else if-else),并且从小到大输出。public class IfTest1 {public static void main(String[] args) {int num1 = Integer.parseInt(args[0]);int num2 = Integer.parseInt(args[1]);int num3 = Integer.parseInt(args[2]);if (num1 > num2){if (num3 > num1){System.out.println(num2 + "," + num1 + "," + num3);} else if (num2 > num3) {System.out.println(num3 + "," + num2 + "," + num1);} else{System.out.println(num2 + "," + num3 + "," + num1);}}else {if (num3 > num2) {System.out.println(num1 + "," + num2 + "," + num3);}else if(num1 > num3) {System.out.println(num3 + "," + num1 + "," + num2);}else {System.out.println(num1 + "," + num3 + "," + num2);}}}}class IfTest11 {public static void main(String[] args) {int num1 = Integer.parseInt(args[0]);int num2 = Integer.parseInt(args[1]);int num3 = Integer.parseInt(args[2]);//比较交换3次//1和2if (num1 > num2) {int tmp = num1;num1 = num2;num2 = tmp;}//2和3if (num2 > num3) {int tmp = num2;num2 = num3;num3 = tmp;}//1和2if (num1 > num2) {int tmp = num1;num1 = num2;num2 = tmp;}System.out.println(num1 + "," + num2 + "," + num3);}}