掌握Java流程控制语句、数组的编程方法。
一、输出月份的英文名
编写一程序，将从键盘输入的每个月份数(整数)显示出其对应的英文，直至输入0结束，注意对非法数据的处理。 (while,switch语句)
//方法一，使用Systrm.in.read()
import java.io.IOException;
public class MonthName
{
public static void main(String args[])
{
int monthNum = 0;
String Str = null;
byte buf[] = new byte[20];
try
{
System.out.print("Please enter a month number:");
System.in.read(buf);
}
catch (IOException e)
{
e.printStackTrace();
}
Str = new String(buf);
monthNum = Integer.parseInt(Str.trim());
while (monthNum != 0)
{
switch (monthNum)
{
case 1:
System.out.println("January");
break;
case 2:
System.out.println("February");
break;
case 3:
System.out.println("March");
break;
case 4:
System.out.println("April");
break;
case 5:
System.out.println("May");
break;
case 6:
System.out.println("June");
break;
case 7:
System.out.println("July");
break;
case 8:
System.out.println("August");
break;
case 9:
System.out.println("September");
break;
case 10:
System.out.println("October");
break;
case 11:
System.out.println("November");
break;
case 12:
System.out.println("December");
break;
default:
System.out.println("You entered a wrong number(not in 1~12)!");
break;
}
try
{
System.out.print("Please enter a month number:");
System.in.read(buf);
}
catch (IOException e)
{
e.printStackTrace();
}
Str = new String(buf);
monthNum = Integer.parseInt(Str.trim());
}
}
}
//方法二，使用Scanner类
import java.util.Scanner;
public class MonthName
{
public static void main(String args[])
{
int monthNum = 0;
System.out.print("Please enter month numbers:");
Scanner scanner = new Scanner(System.in);
if (scanner.hasNext())
{
monthNum = Integer.parseInt(scanner.next());
}
while (monthNum!=0)
{
switch (monthNum)
{
case 1:
System.out.println("January");
break;
case 2:
System.out.println("February");
break;
case 3:
System.out.println("March");
break;
case 4:
System.out.println("April");
break;
case 5:
System.out.println("May");
break;
case 6:
System.out.println("June");
break;
case 7:
System.out.println("July");
break;
case 8:
System.out.println("August");
break;
case 9:
System.out.println("September");
break;
case 10:
System.out.println("October");
break;
case 11:
System.out.println("November");
break;
case 12:
System.out.println("December");
break;
default:
System.out.println("Please enter the numbers 1~12!");
break;
}
if (scanner.hasNext())
{
monthNum = Integer.parseInt(scanner.next());
}
}
scanner.close();
}
}
二、打印水仙花数
打印出所有的“水仙花数”。所谓“水仙花数”是指一个三位数，其各位数字的立方和等于该数本身。例如153是一个“水仙花数”，因为153=13+53+33。
public class NarcissisticNumber
{
public static void main(String args[])
{
System.out.println("The 3-digit narcissistic numbers:");
for (int i = 100; i < 1000; i++)
{
int unit = i % 10;
int decade = i / 10 % 10;
int hundred = i / 100;
int judge = (int) (Math.pow(unit,3)+Math.pow(decade,3)+Math.pow(hundred,3));
if (judge==i)
{
System.out.println(i)
};
}
}
}
三、统计特定数字
统计个位数是6，并且能被3整除的五位数共有多少个。
public class CountNumbers
{
public static void main(String args[])
{
/* int count = 0;
for (int i = 1000; i <9999 ; i++)
{
String Str =""+i+6;
int number = Integer.parseInt(Str);
if (number%3==0)
{
count++;
}
}
System.out.print("The number is "+count);*/
int count = 0;
for (int i = 10006; i <99996 ; i+=10)
{
if (i%3==0)
{
count++;
}
}
System.out.print("The number is "+count);
}
}
四、一维数组排序
编写一个程序，在其中建立一个有10个整数的数组，运行后从键盘输入10个数，然后排序(升序)后输出。
import java.util.Arrays;
import java.util.Scanner;
public class Sort
{
public static void main(String args[])
{
int array[] = new int[10];
System.out.println("请输入10个整数:");
Scanner scanner = new Scanner(System.in);
for (int i = 0; i < 10; i++)
{
if (scanner.hasNext())
{
array[i] = Integer.parseInt(scanner.next());
}
}
System.out.println("排序结果:");
Arrays.sort(array);
for (int i = 0; i <10 ; i++)
{
System.out.print(array[i]+" ");
}
}
}
五、计算矩阵每行之和
编写一个程序，计算出5行5列整数矩阵的每行之和。
import java.util.Scanner;
public class MatrixSum
{
public static void main(String args[] )
{
Scanner scanner = new Scanner(System.in);
int matrix[][] = new int[5][5];
for(int i = 0;i < 5;i++)
{
for (int j = 0; j < 5; j++)
{
if (scanner.hasNext())
{
matrix[i][j] = Integer.parseInt(scanner.next());
}
}
}
for(int i = 0;i < 5;i++)
{
int sum = 0;
for (int j = 0; j < 5; j++)
{
sum = sum + matrix[i][j];
}
System.out.println(sum);
}
}
}