JavaSE part1 基础程序设计day06

4_1

代码：

public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int positiveCount=0;//正数个数
		int negativeCount=0;//负数个数
		int sum=0;//总和
		double average=0;//平均值
		System.out.print("Enter an integer,the input ends if it is 0:");
		while(true){
			int num=scanner.nextInt();
			if(num<0){
				negativeCount++;
			}else if(num>0){
				positiveCount++;
			}else{
				break;
			}
			sum=sum+num;
		}
		average=1.0*sum/(negativeCount+positiveCount);
		System.out.println("The number of positive is "+positiveCount);
		System.out.println("The number of negative is "+negativeCount);
		System.out.println("The total is "+sum);
		System.out.println("The average is "+average);
	}

4_2

代码：

public static void main(String[] args){
		Scanner scanner=new Scanner(System.in);
		int firstScore=0,secondScore=0;
		String firstName="",secondName="";
		System.out.print("Enter the number of the students:");
		int count=scanner.nextInt();
		System.out.print("Enter the name and score:");
		for(int i=0;i<count;i++){
			String name=scanner.next();
			int score=scanner.nextInt();
			if(score>=firstScore){
				secondScore=firstScore;
				secondName=firstName;
				firstScore=score;
				firstName=name;
			}else if(score>=secondScore){
				secondScore=score;
				secondName=name;
			}
		}
		System.out.println(firstName+" : "+firstScore);
		System.out.println(secondName+" : "+secondScore);
	}

4_3

代码：

public static void main(String[] args){
		int count=0;
		for(int i=100;i<=200;i++){
			if(i%5==0||i%6==0&&i%5==0^i%6==0){
				System.out.print(i+" ");
				count++;
				if(count%10==0){
					System.out.println();
				}
			}
		}
	
	}

4_4

代码：

public static void main(String[] args) {
		int n=1;
		while(n*n<=12000){
			n++;
		}
		System.out.println(109*109);
		System.out.println(n);
		n=1;
		while(n*n*n<=12000){
			n++;
		}
		System.out.println(n*n*n);
		System.out.println(n-1);
		System.out.println(22*22*22);
	}

4_5

代码：

public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		System.out.print("Enter a number:");
		int number=scanner.nextInt();
		while(true){
			boolean flag=false;
			for(int i=2;i<number/2;i++){
				if(number%i==0){
					System.out.print(i+" ");
					number/=i;
					flag=true;
					break;
				}
			}
			if(!flag){
				System.out.print(number);
				break;
			}
		}
	}

4_6

代码：

public static void main(String[] args){
		Scanner scanner=new Scanner(System.in);
		System.out.print("Enter the line:");
		int line=scanner.nextInt();
		for(int i=1;i<=line;i++){
			for(int k=1;k<=line-i;k++){
				System.out.print("   ");
			}
			for(int j=-i;j<=i;j++){
				if(j!=0&&j!=1){
					System.out.printf("%-3d",Math.abs(j));
				}
			}
			System.out.println();
		}
	}

4_8

代码：

public static void main(String[] args){
		Scanner scanner=new Scanner(System.in);
		System.out.print("Enter the line:");
		int line=scanner.nextInt();
		for(int i=1;i<=line;i++){
			for(int k=1;k<=line-i;k++){
				System.out.print("    ");
			}
			for(int j=-(i-1);j<=i-1;j++){
				if(j<=0){
					System.out.printf("%-4d",(int)Math.pow(2,j+i-1));
				}else{
					System.out.printf("%-4d",(int)Math.pow(2,-j+i-1));
				}
			}
			System.out.println();
		}
	}

ScanneDemo:

public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		//无论用户输入的是什么数据 都以字符串先获取
		System.out.print("Enter:");
		//"10 20"->"10""20"->"10"->double
		String a=scanner.next();//返回的是第一个字符串
		double b=scanner.nextDouble();
		String c=scanner.next();
		System.out.println(a+b+c);
		//"1 2 3 4"
		System.out.println(Integer.parseInt("abc"));
		//"10 20 30 回车"
		scanner.nextLine();//吃掉回车
		System.out.print("Enter line:");
		String s=scanner.nextLine();
		System.out.println("["+s+"]");
	}