Java基础篇运算符与if判断

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class Demo_1 
{
	public static void main(String[] arg)
	{
		int a = 1;
		int b = 2;
		//先赋值 再运算
		int aplus = a++;
		int bplus = b--;
		System.out.println("aplus  "+aplus);
		System.out.println("bplus  "+bplus);
		System.out.println("a---"+a);
		System.out.println("b---"+b);

		//先运算 再赋值
		int aa = ++a;
		int bb = --b;
		System.out.println("a---"+a);
		System.out.println("b---"+b);
		System.out.println("aplus  "+aa);
		System.out.println("bplus  "+bb);
	}
}

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import java.util.Scanner;
class Demo_3 
{
	public static void main(String[] args) 
	{
	Test1();
	}
	public static void Test1()
	{
		Scanner sc = new Scanner(System.in);
		int age = sc.nextInt();
		System.out.println(age>18 && age<60);
	}
	public static void Test2()
	{
		Scanner sc = new Scanner(System.in);
		int age = sc.nextInt();
		System.out.println(age<12 || age>60);
	}
	public static void Test3()
	{
		Scanner sc = new Scanner(System.in);
		System.out.println("A:输入等于或大于90 但小于100的数");
		int a=sc.nextInt();
		System.out.println(a>=90 && a<100);
		System.out.println("B:输入不是字符q 也不是字符k的字符");
		String b = sc.next();
		System.out.println(b.charAt(0)!='q' && b.charAt(0)!='k');

		System.out.println("C:输入1~9 但不包括5 的数");
		int c = sc.nextInt();
		System.out.println((c>1 && c<9) && c!=5);

		System.out.println("D:输入一个不是1~9的数字");
		int d = sc.nextInt();
		System.out.println(d<1 && d>9);
	}
	public static void Tedt4()
	{
		Scanner sc = new Scanner(System.in);
		int year = sc.nextInt();
		System.out.println(((year % 4 == 0) && year % 100 == 0) && year % 400 == 0);
	}
	public static void Test5()
	{
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		char c = s.charAt(0);
		System.out.println(c>65 && c<90);
	}
}

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class Demo_4 
{
	public static void main(String[] args) 
	{
		//1.用三目运算符 比较两个整数是否相等
		int a = 10;
		int b = 20;
		boolean b1 = (a==b) ? true : false;
		System.out.println(b1);

		//2.获取三个整数中的最大值
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		int temp = (a>b)?a:b;
		int max = (temp>c)?temp:c;
		System.out.println(max);
	}
}

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import java.util.Scanner;
class Demo_6 
{
	public static void main(String[] args) 
	{
		Scanner sc= new Scanner(System.in);
		/*int a=sc.nextInt();
		int b= sc.nextInt();
		if(a>b)
		{
			System.out.println(a+" "+b);
		}
		if(b>a)
		{
			System.out.println(b+""+a);
		}*/
		/*int c= sc.nextInt();
		if(c%2==0)
		{
			System.out.println(c+"是偶数");
		}
		else
		{
			System.out.println(c+"是奇数");
		}*/
		String s= sc.next();
		char a=s.charAt(0);
		if(a=>65&&a<=90)
		{
			a +=32;
		}
		System.out.println(a);
		//System.out.println("哥们儿,rn最近还好吗?t有没有看rn"星球大战"?'男'猪脚\叫什么来着?");
	}
}

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import java.util.Scanner;
import java.lang.Math;
class Homework 
{
	public static void main(String[] args) 
	{
		homework2();
	}
	public static void homework1()
	{
		Scanner sc = new Scanner(System.in);
		int a= sc.nextInt();
		if(a==1)
		{
			System.out.println("今天是星期一");
		}
		if(a==2)
		{
			System.out.println("今天是星期二");
		}
		if(a==3)
		{
			System.out.println("今天是星期三");
		}
		if(a==4)
		{
			System.out.println("今天是星期四");
		}
		if(a==5)
		{
			System.out.println("今天是星期五");
		}
		if(a==6)
		{
			System.out.println("今天是星期六");
		}
		if(a==7)
		{
			System.out.println("今天是星期天");
		}
	}
	public static void homework2()
	{
		Scanner sc= new Scanner(System.in);
		int a=sc.nextInt();
		int k=(int)Math.sqrt(a);
		int i;
		for(i=2;i<=k;i++)
		{
			if(a%i==0)
				break;
		}
		if(i>k)
			System.out.println("这个数是质数");
		else
			System.out.println("这个数不是质数");
	}
}