如果是刚接触或者刚学习java，练习一些基础的算法还是必须的，可以提升思维和语法的使用。
1、输出两个int数中的最大值
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请依次输入两个整数：a,b（以空格隔开）”);
int a = scanner.nextInt();
int b = scanner.nextInt();
int max;
if(a >= b){
max = a;
}else {
max = b;
}
System.out.println(“最大值为”+max);
}
}
}
2、输出三个int数中的最大值
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请依次输入两个整数：a,b（以空格隔开）”);
int a = scanner.nextInt();
int b = scanner.nextInt();
int c = scanner.nextInt();
scanner.close();
int d=(a>b)?a:b;
int e=(d>c)?d:c;
System.out.println(“最大值为”+e);
if(a>b && a>c){
System.out.println(“最大值为”+a);
}else if(b>c && b>a){
System.out.println(“最大值为”+b);
}else if(c>b && c>a){
System.out.println(“最大值为”+c);
}else{
System.out.println(“出现异常”);
}
}
}
3、编写程序判断某一个年份是否是闰年
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请输入年份：”);
int year = scanner.nextInt();
if((year % 4 ==0 && year % 100 !=0) || year%400 ==0){
System.out.println(“这个年份是闰年”);
}else{
System.out.println(“这个年份不是闰年”);
}
boolean isLeapYear = (year % 4 ==0 && year % 100 !=0) || year%400 ==0;
String string = isLeapYear?year+”是闰年”:year+”不是闰年”;
System.out.println(string);
}
}
4、完成成绩等级输出程序
如果用户输入的分数正确（0-100），则根据表-1中的规则计算该分数所对应的的级别，并计算结果。
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请输入分数：”);
double score = scanner.nextDouble();
scanner.close();
if(score < 0 || score >100){
System.out.println(“输入的分数不在0-100之间，不符合要求”);
}else if(score >= 90){
System.out.println(“A”);
}else if(score >= 80){
System.out.println(“B”);
}else if(score >= 60){
System.out.println(“C”);
}else{
System.out.println(“D”);
}
}
}
5、完成命令解析程序
问题：有一个命令解析程序，该程序提供三个功能选型供用户选择，用户选择某功能后，程序在界面上输出用户所选择的的功能名称。程序的交互如图：
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请选择功能：1.显示全部记录 2.查询登录记录 0.退出”);
int command = scanner.nextInt();
scanner.close();
switch (command) {
case 0:
System.out.println(“欢迎使用”);
break;
case 1:
System.out.println(“显示全部记录……”);
break;
case 2:
System.out.println(“查询登录记录……”);
break;
default:
System.out.println(“输入错误！”);
}
}
}
6、完成收银柜台收款程序
编写一个收银柜台收款程序。根据单价、购买数量以及收款进行计算并输出应收金额和找零；当总价大于或者等于500，享受8折优惠。控制台交互如下：
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请输入单价（￥）:”);
double price = scanner.nextDouble();
System.out.println(“请输入数量：”);
double amount = scanner.nextDouble();
System.out.println(“请输入收款金额：”);
double count = scanner.nextDouble();
double totalMoney = price*amount;
if(totalMoney > 500){
totalMoney = totalMoney*0.8;
}
double change = count – totalMoney;
System.out.println(“应收金额为：”+totalMoney + “找零为：”+change);
}
}
7、java从键盘输入三个整数,实现从小到大排序
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请输入三个整数，以空格隔开：”);
int a = scanner.nextInt();
int b = scanner.nextInt();
int c = scanner.nextInt();
scanner.close();
System.out.println(“输入的值为：a = ” + a + “, b = ” + b + “, c = ” + c);
if(a > b){
if ( b > c) {
System.out.println(“排序后的值为：” + c + “,” + b + “,” + a);
}else if( c > a){
System.out.println(“排序后的值为：” + b + “,” + a + “,” + c);
}else{
System.out.println(“排序后的值为：” + b + “,” + a + “,” + c);
}
}else{
if(c < a){
System.out.println(“排序后的值为：” + c + “,” + a + “,” + b);
}else if(c > b){
System.out.println(“排序后的值为：” + a + “,” + b + “,” + c);
}else{
System.out.println(“排序后的值为：”+ a + “,” + c + “,” + b);
}
}
}
}
8、计算个人所得税
北京地区的个人所得税计算公式：
纳税额 = （工资薪金所得 – 扣除数）*适用税率 – 速算扣除数
其中，扣除数为3500，适用税率以及速算扣除数如下表所示：
package demo;
import java.util.Scanner;
public class demo {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请输入你的税前工资：”);
int salaryBeforeTax = scanner.nextInt();
scanner.close();
int taxSalary = salaryBeforeTax – 3500;
double tax;
tax = taxSalary<0?0.0:
taxSalary<=1500?taxSalary*0.03:
taxSalary<=4500?taxSalary*0.1-105:
taxSalary<=9000?taxSalary*0.2-555:
taxSalary<=35000?taxSalary*0.25-1005:
taxSalary<=55000?taxSalary*0.3-2755:
taxSalary<=80000?taxSalary*0.35-5505:
taxSalary*0.45-13505;
System.out.println(“个人应缴纳税款为：”+tax);
if( taxSalary < 0 ){
tax = 0;
}else if( taxSalary <= 1500){
tax = taxSalary*0.03;
}else if( taxSalary <= 4500){
tax = taxSalary*0.1-105;
}else if( taxSalary <= 9000){
tax = taxSalary*0.2-555;
}else if( taxSalary <= 35000){
tax = taxSalary*0.25-1005;
}else if( taxSalary <= 55000){
tax = taxSalary*0.3-2755;
}else if( taxSalary <= 80000){
tax = taxSalary*0.35-5505;
}else{
tax = taxSalary*0.45-13505;
}
System.out.println(“个人应缴纳税款为：”+tax);
}
}
9、输入年份和月份，输出天数
package demo;
import java.util.Scanner;
public class demo{
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println(“请输入年份：”);
int year = scanner.nextInt();
System.out.println(“请输入月份：”);
int month = scanner.nextInt();
int dayNum = theDayNum(month); //先根据月份得出天数，如果是闰年，对2月份的天数重新获取
if(isLeapYear(year)){
if(month == 2){
dayNum ++; //如果是闰年，2月份增加一天
}
System.out.print(year + “是闰年，”);
}else{
System.out.print(year + “不是闰年，”);
}
System.out.println(year + “年” + month + “月份共有” + dayNum + “天”);
}
public static boolean isLeapYear(int year) {
if((year % 4 ==0 && year % 100 !=0) || year%400 ==0){
return true;
}else{
return false;
}
}
public static int theDayNum(int month) {
switch (month) {
case 1:
return 31;
case 2:
return 28;
case 3:
return 31;
case 4:
return 30;
case 5:
return 31;
case 6:
return 30;
case 7:
return 31;
case 8:
return 31;
case 9:
return 30;
case 10:
return 31;
case 11:
return 30;
case 12:
return 31;
default:
System.out.println(“对不起，您输入的月份有误！”);
return 0;
}
}
}
10、输出九九乘法表
package demo;
public class demo {
public static void main(String[] args) {
//i变量用于控制行数
for(int i = 0; i <= 9; i++) {
//j变量用于控制每行中参与计算的数值
for(int j = 1; j <= i; j++) {
System.out.print(j + “*” + i + “=” + i*j + “t”);
}
//每行输出之后需要换行
System.out.println();
}
}
}
11、随机产生一个从0-100之间的整数，判断是否是质数
质数又称素数,是指在一个大于1的自然数中，除了1和此整数自身外，不能被其他自然数整除的数 。
package demo;
import java.util.Random;
public class primeNum {
public static void main(String[] args) {
int num;
Random random = new Random();
num = random.nextInt(100);
System.out.println(“随机产生的数为：” + num);
System.out.println(isPrime(num));
}
public static boolean isPrime(int num) {
if(num < 2) {
return false;
}
if(num == 2) {
return true;
}
if(num % 2 == 0) {
return false;
}
for(int i = 3; i <= Math.sqrt(num); i += 2) {
if(num % i == 0) {
return false;
}
}
return true;
}
}
12、查找数组最小值，并将数组扩容成新数组
package demo;
import java.util.Arrays;
import java.util.Random;
public class copyOf {
public static void main(String[] args) {
int [] arr = new int[10];
//随机产生10个 0-100之间的整数
Random random = new Random();
for(int i = 0; i < 10; i ++) {
arr[i] = random.nextInt(100);
}
//打印数组的内容
System.out.println(“随机产生的数组为：” + Arrays.toString(arr));
//查找最小的值
int min = arr[0];
for(int j = 1; j < 10; j ++) {
if(min > arr[j]) {
min = arr[j];
}
}
System.out.println(“该数组最小的值为：” + min);
//扩容，将最小值存在扩容之后的第一个
int [] newArr = Arrays.copyOf(arr, 11);
//从后往前遍历，将前面的值赋给后面的值，然后将第一个的值赋为最小值min
for(int k = newArr.length-1; k >=1; k –) {
newArr[k] = newArr[k-1];
}
//将第一个的值赋为最小值min
newArr[0] = min;
//打印数组的内容
System.out.println(“扩容之后的数组为：”+ Arrays.toString(newArr));
}
}
