Java程序设计简单练习题
整理了一下最近做的Java练习题，编程新手请多指教
1、编写一个实现由1到k的平方和计算
package demo1.code1;
import java.util.Scanner;
public class Calculate_k {
public static int calculation(int k) {
int result = 0;
for (int i = 1; i <= k; i++) {
result = i * i + result;
}
return result;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int result;
int num;
System.out.print("输入一个整数:");
num = sc.nextInt();
result = calculation(5);
System.out.println(result);
}
}
2.用Java描述一个三角形，提供计算三角形面积方法。三角形的三个边长从键盘输入。
package demo1.code1;
import java.util.Scanner;
public class Triangle {
private double a, b, c; //三角形的三条边的边长
public Triangle(double aa, double bb, double cc) {
a = aa;
b = bb;
c = cc;
}//构造函数
public double getArea() {
double p;
double s;
p = (a + b + c) / 2;
s = p * (p - a) * (p - b) * (p - c);
s = Math.sqrt(s);
return s;
}//计算三角形面积
public static void main(String[] args) {
double a, b, c;
double s;
Scanner sc = new Scanner(System.in);
System.out.print("请输入三角形的三条边：");
a = sc.nextInt();
b = sc.nextInt();
c = sc.nextInt();
Triangle tri = new Triangle(a, b, c);
s = tri.getArea();
System.out.println(s);
}
}
3.假如今天是星期二，100天后将是星期几？
package demo1.code1;
public class CountDate {
public static void main(String[] args) {
int days = 100;
int d;
d = days % 7;
System.out.println("假设今天是星期二");
switch (d) {
case 0:
System.out.println("今天的100天后是星期二");
break;
case 1:
System.out.println("今天的100天后是星期三");
break;
case 2:
System.out.println("今天的100天后是星期四");
break;
case 3:
System.out.println("今天的100天后是星期五");
break;
case 4:
System.out.println("今天的100天后是星期六");
break;
case 5:
System.out.println("今天的100天后是星期日");
break;
case 6:
System.out.println("今天的100天后是星期一");
break;
}
}
}
4.人民币的面值有100元，50元，20元，10元，5元，1元，5角，1角，5分，1分。编写程序实现从键盘输入1万元以内的任意数，然后分解成不同数量的，不同面值的人民币？
package demo1.code1;
import java.util.Scanner;
public class RMBDivision {
public static void main(String[] args) {
double rmb;
int rmb_left;
int rmb_fj;
int hundred = 10000;
int fif = 5000;
int ten = 1000;
int fiv = 500;
int one = 100;
double fivej = 50;
double onej = 10;
double fivef = 5;
Scanner sc = new Scanner(System.in);
System.out.print("请输入人民币数值（单位：元）：");
rmb = sc.nextDouble();
rmb_left = (int) rmb;
rmb = rmb - rmb_left;
rmb_left = rmb_left * 100; //将用户输入的人民币单位从元化作分
rmb = rmb * 100;
rmb_fj = (int) rmb;
hundred = rmb_left / hundred;
rmb_left = rmb_left - hundred * 10000;
fif = rmb_left / fif;
rmb_left = rmb_left - fif * 5000;
ten = rmb_left / ten;
rmb_left = rmb_left - ten * 1000;
fiv = rmb_left / fiv;
rmb_left = rmb_left - fiv * 500;
one = rmb_left / one;
rmb_left = rmb_left - one * 100;
fivej = rmb_fj / (int) fivej;
rmb_fj = rmb_fj - (int) fivej * 50;
onej = rmb_fj / (int) onej;
rmb_fj = rmb_fj - (int) onej * 10;
fivef = rmb_fj / (int) fivef;
rmb_fj = rmb_fj - (int) fivef * 5;
System.out.println("该数值的人民币可分解为" + hundred + "张一百元，" + fif + "张五十元，" + ten + "张十元，" + fiv + "张五元，" +
one + "张一元，" + (int) fivej + "张五角，" + (int) onej + "张一角，" + (int) fivef + "张五分，" + rmb_fj + "张一分纸币。");
}
}
5.编写程序，提示输入两点（x1,y1）和（x2,y2），然后计算两点之间的距离。
package demo1.code1;
import java.util.Scanner;
public class DistanceOfTwoPoints {
public static double distance(double a, double b, double c, double d) {
double distance;
distance = Math.sqrt((a - c) * (a - c) + (b - d) * (b - d));
return distance;
}
public static void main(String[] args) {
double a, b, c, d;
double dist;
Scanner sc = new Scanner(System.in);
System.out.println("请输入第一个点的横坐标与纵坐标（空格键隔开）：");
a = sc.nextDouble();
b = sc.nextDouble();
System.out.println("请输入第二个点的横坐标与纵坐标（空格键隔开）：");
c = sc.nextDouble();
d = sc.nextDouble();
dist = distance(a, b, c, d);
System.out.print("两点之间的距离为：" + dist);
}
}
6.已知三角形的底边和高尺寸分别是56厘米、120厘米，计算该三角形的面积？
package demo1.code1;
public class Triangle02 {
private double bottom, height; //三角形的底边和高
public Triangle02(double b, double h) {
bottom = b;
height = h;
}//构造函数
public double getArea() {
double s;
s = bottom * height / 2;
return s;
}
public static void main(String[] args) {
double result;
Triangle02 tri = new Triangle02(56, 120);
result = tri.getArea();
System.out.println("三角形的面积为" + result + "平方厘米。");
}
}
7.从键盘输入三个整数，分别计算它们的平均值、累加和、最大值和最小值。
package demo1.code1;
import java.util.Scanner;
public class ThreeNumCalculation {
public static int Sum(int a, int b, int c) {
int result;
result = a + b + c;
return result;
}
public static int Average(int a, int b, int c) {
int result;
result = (a + b + c) / 3;
return result;
}
public static int Max(int a, int b, int c) {
int max;
if (a > b) {
max = a;
} else {
max = b;
}
if (max > c) {
return max;
} else {
return c;
}
}
public static int Min(int a, int b, int c) {
int min;
if (a < b) {
min = a;
} else {
min = b;
}
if (min < c) {
return min;
} else {
return c;
}
}
public static void main(String[] args) {
int a, b, c;
int result;
Scanner sc = new Scanner(System.in);
System.out.println("请输入三个整数：");
a = sc.nextInt();
b = sc.nextInt();
c = sc.nextInt();
result = Average(a, b, c);
System.out.println("三个数的平均值为：" + result);
result = Sum(a, b, c);
System.out.println("三个数的累加和为：" + result);
result = Max(a, b, c);
System.out.println("三个数中的最大值为：" + result);
result = Min(a, b, c);
System.out.println("三个数中的最小值为：" + result);
}
}
8.已知圆的半径为R，从键盘输入R的值，分别计算圆的面积和周长。
package demo1.code1;
import java.util.Scanner;
public class Circle {
private double radius;
public Circle(double R) {
radius = R;
}
public double getCircumference() {
return 2 * 3.14 * radius;
}
public double getArea() {
return 3.14 * radius * radius;
}
public static void main(String[] args) {
double result;
double R;
Scanner sc = new Scanner(System.in);
System.out.println("请输入圆半径大小：");
R = sc.nextDouble();
Circle cir = new Circle(R);
result = cir.getArea();
System.out.println("圆的面积为：" + result);
result = cir.getCircumference();
System.out.println("圆的周长为：" + result);
}
}
9.编写程序生成15个随机（int类型）整数?
package demo1.code1;
import java.util.Random;
public class FifteenRandomInt {
public static void main(String[] args) {
int num;
Random ran = new Random();
for (int i = 0; i < 15; i++) {
num = ran.nextInt(100);
System.out.print(num + " ");
}
}
}
10.有一三角形的三个顶点A(x,y)、B(x,y)和C(x,y)，编写程序从键盘输入三个顶点的坐标，然后计算这个三角形的三个边长和面积？
package demo1.code1;
import java.util.Scanner;
public class Triangle03 {
private double fir_x, fir_y;
private double sec_x, sec_y;
private double thi_x, thi_y;
public Triangle03(double fx, double fy, double sx, double sy, double tx, double ty) {
fir_x = fx;
fir_y = fy;
sec_x = sx;
sec_y = sy;
thi_x = tx;
thi_y = ty;
}
public static double distance(double a, double b, double c, double d) {
double distance;
distance = Math.sqrt((a - c) * (a - c) + (b - d) * (b - d));
return distance;
}
public double getPerimeter() {
double dist1 = distance(fir_x, fir_y, sec_x, sec_y);
double dist2 = distance(fir_x, fir_y, thi_x, thi_y);
double dist3 = distance(sec_x, sec_y, thi_x, thi_y);
return dist1 + dist2 + dist3;
}
public double getArea() {
double p;
double s;
double dist1 = distance(fir_x, fir_y, sec_x, sec_y);
double dist2 = distance(fir_x, fir_y, thi_x, thi_y);
double dist3 = distance(sec_x, sec_y, thi_x, thi_y);
p = (dist1 + dist2 + dist3) / 2;
s = p * (p - dist1) * (p - dist2) * (p - dist3);
s = Math.sqrt(s);
return s;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
double a, b, c, d, e, f;
System.out.print("请输入三角形第一个顶点坐标（空格键隔开）：");
a = sc.nextDouble();
b = sc.nextDouble();
System.out.print("请输入三角形第二个顶点坐标（空格键隔开）：");
c = sc.nextDouble();
d = sc.nextDouble();
System.out.print("请输入三角形第三个顶点坐标（空格键隔开）：");
e = sc.nextDouble();
f = sc.nextDouble();
Triangle03 tri = new Triangle03(a, b, c, d, e, f);
System.out.println("该三角形的周长为：" + tri.getPerimeter());
System.out.println("该三角形的面积为：" + tri.getArea());
}
}
11.编写程序，提示从键盘输入一个字符串，然后显示字符串的长度及第一个和最后一个字符？
package demo1.code1;
import java.util.Scanner;
public class StringLength {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str = new String();
int length;
System.out.print("请输入一个字符串：");
str = sc.nextLine();
length = str.length();
char[] c = str.toCharArray();
char last_char = c[length - 1];
System.out.println("该字符串长度为：" + length);
System.out.println("该字符串最后一个字符为：" + last_char);
}
}
12.编写程序，提示从键盘输入两个字符串，然后检测第二个字符串是否包含于第一个串中？例如，字符串“Lambda expressions let you express instances of single-method classes more compactly.”和“express”，其中“express”包含于第一个字符串内。
package demo1.code1;
import java.util.Scanner;
public class TwoStringsContains {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str1, str2;
System.out.print("请输入第一个字符串：");
str1 = sc.nextLine();
System.out.print("请输入第二个字符串：");
str2 = sc.nextLine();
if (str1.contains(str2)) {
System.out.println("第二个字符串包含于第一个字符串内。");
} else {
System.out.println("第二个字符串不包含于第一个字符串内。");
}
}
}
13.编写程序生成2016个随机（int类型）整数，然后按“升序”排序？
package demo1.code1;
import java.util.Arrays;
import java.util.Random;
public class RandomInt2016 {
public static void main(String[] args) {
int num;
Random ran = new Random();
int[] array = new int[2016];
for (int i = 0; i < 2016; i++) {
num = ran.nextInt(2000);
array[i] = num;
}
Arrays.sort(array);
System.out.println(Arrays.toString(array));
}
}
14.编写一个Java类实现查找1～n之间的素数?
package demo1.code1;
import java.util.Scanner;
public class OneToNPrime {
public static void findPrime(int num) {
boolean isPrime = true;
for (int i = 2; i <= num; i++) {
for (int j = 2; j < i; j++) {// 不能写j<=i,任何数都能被自身整除
if (i % j == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
System.out.print(i + " ");
}
isPrime = true;
}
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num;
System.out.println("请输入一个正整数：");
num = sc.nextInt();
System.out.println("1~" + num + "之间的素数有：");
findPrime(num);
}
}
15.阶乘函数f(n)=n!,其中n为正整数。试设计一个计算阶乘的方法，并计算f(5)和f(10)的值。
package demo1.code1;
import java.util.Scanner;
public class CalculateFactorial {
public static int calculateFactorial(int num) {
int result = 1;
for (int i = 1; i <= num; i++) {
result = result * i;
}
return result;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int result;
int num;
System.out.println("请输入一个正整数：");
num = sc.nextInt();
result = calculateFactorial(num);
System.out.println(num + "!=" + result);
}
}
16.有整数M，求出小于M的所有素数？
package demo1.code1;
import java.util.Scanner;
public class CalculateFactorial {
public static int calculateFactorial(int num) {
int result = 1;
for (int i = 1; i <= num; i++) {
result = result * i;
}
return result;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int result;
int num;
System.out.println("请输入一个正整数：");
num = sc.nextInt();
result = calculateFactorial(num);
System.out.println(num + "!=" + result);
}
}
17、利用下列数列计算圆周率的近似值。
package demo1.code1;
import java.util.Scanner;
public class CalculateΠ {
public static double calculate(int num) {
double result = 1;
double sign = -1;// 如果sign是int类型的话会造成数据精度丢失
for (int i = 2; i <= num; i++) {
result = result + (sign / (2 * i - 1));
sign *= (-1);
}
result *= 4;
return result;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num;
System.out.println("请输入一个整数：");
num = sc.nextInt();
System.out.println("圆周率的近似值为：" + calculate(num));
}
}