java实例一
java中有三种方式向控制台输入信息，分别是print，printf,println,现在简单介绍一下他们之间的异同。
- printf主要是继承了C语言的printf的一些特性，可以进行格式化输出
- print就是一般的标准输出，但是不换行
- println和print基本没什么差别，就是最后会换行
1.1计算最大值
public static void main(String[] args) {
int num1 = 34;
int num2 = 56;
int max = (num1>num2)?num1:num2;
String equals = num1==num2?"the same number":"not the same number";
System.out.println(max);
System.out.println(equals);
}
1.2计算长方形面积
public static void main(String[] args) {
double width = 38.6;
double longth = 42.5;
System.out.println("The width is "+width);
System.out.println("The longth is " + longth);
double area = width * longth;
System.out.println("The area is " + area);
}
1.3计算圆形面积
public static void main(String[] args) {
double r=18;
final double PI=3.1415926;
double area = PI*r*r;
System.out.println(area); // 1017.8760024
}
1.4计算移位
byte value = 1;
int bit1 = value;
int bit2 = value<<1;
int bit3 = value<<2;
int bit4 = value<<3;
System.out.println(bit2+"+"+bit3+"+"+bit4); // 2+4+8
1.5强制类型转换
long num=33333;
System.out.println((int)num);
System.out.println((short)num);
System.out.println((byte)num);
System.out.println((float)num);
System.out.println((char)num);
1.6计算公约数
公约数，亦称“公因数”。它是一个能被若干个整数同时均整除的整数。如果一个整数同时是几个整数的约数，称这个整数为它们的“公约数”；公约数中最大的称为最大公约数。对任意的若干个正整数，1总是它们的公因数。
方法一：python:
1，2，5，10public static void main(String[] args) {
int num1 = 14;
int num2 = 98;
for(int i=1;i<=num1&&i<=num2;i++) {
if (num1%i==0 && num2%i ==0) {
System.out.println("The number i\t" + i);
}
}
1.7输出100以内能被7整除的数
public static void main(String[] args) {
System.out.println("The number can be divided by 7 from 1 to 100");
for(int i=1;i<=100;i++) {
if(i%7==0) {
System.out.println("This number is "+i );
}
}
1.8实现一个计算阶乘的方式，公式为"n!=n*(n-1)*(n-2)···*2*1"
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int n = input.nextInt();
long result = 1;
if(n<0||n>17) {
System.out.println("The number need between the 1 to 16");
}else if(n==0) {
System.out.println("The factorial 0 is "+result );
}else {
for(int i=n;i>0;i--) {
result*=i;
}
System.out.println("The result is " + result);
}
1.9输出素数40个数，并且每行10个
public class Example {
public static void main(String[] args) {
final int PRIMES_NUMBER=40;
final int COUNTER=10;
int count=0;
int number=2;
while(count<PRIMES_NUMBER) {
boolean isPrime=true;
for(int i=2;i<=number/2;i++) {
if(number%i==0) {
isPrime = false;
break;
}
}
if(isPrime) {
count++;
System.out.print(number+"\t");
if(count%COUNTER == 0) {
System.out.println();
}
}
number++;
}
}
}
1.10 判断区别++x and x++
public static void main(String[] args) {
// TODO Auto-generated method stub
int sum = 0;
int x = 1;
while(x<5) {
//sum += x++;
sum += ++x;
System.out.println(sum+"-"+x);
}
System.out.println("The sum and x are "+sum+"\t"+x);
}
1.10 通过年份计算生肖
package basicProject;
import java.util.Scanner;
public class Example3 extends Example2 {
public static void animals(int year) {
switch(year % 12) {
case 2:
System.out.println("It is Dog");
break;
case 3:
System.out.println("It is Pig");
break;
case 4:
System.out.println("It is Mouse");
break;
case 5:
System.out.println("It is Cow");
break;
case 6:
System.out.println("It is tiger");
break;
case 7:
System.out.println("It is Rabbit");
break;
case 8:
System.out.println("It is Dragon");
break;
case 9:
System.out.println("It is Snake");
break;
case 10:
System.out.println("It is horse");
break;
case 11:
System.out.println("It is sheep");
break;
case 0:
System.out.println("It is Monkey");
break;
case 1:
System.out.println("It is chicken ");
break;
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
int userNum = input.nextInt();
Example3 animal_result = new Example3();
animal_result.animals(userNum);
}
}
