如何查找循环中最小和最大的数字？

Question

我需要从我的while循环接收的输入中找到最小和最大的值。我不知道该怎么做。 这是我有：

import java.text.NumberFormat; 
import java.io.*; 
import java.text.DecimalFormat; 
import java.util.Scanner; 

public class average { 
    public static void main(String[] args) { 

     Scanner keyboard = new Scanner(System.in); 
     int count = 0; 
     double ng = 0, total = 0, average; 
     int countt; 
     { 
     BufferedReader input = new BufferedReader (new InputStreamReader(System.in)); 
     } 
     while (ng > -1) { 
      if (ng > -1) 
      System.out.print("Enter your next grade (-1 to quit) : "); 
      ng = keyboard.nextDouble(); 
      total = total + ng; 
      count++; 
     } 
     countt=count-1; 
     average = (total + 1)/countt; 
     System.out.println(" "); 
     System.out.println("Total number of students: " + countt); 
     System.out.println("Average of grades " + average); 
     System.out.println("Highest grade " +); 

    } 
} 

Answer 1

 import java.text.NumberFormat; 
import java.io.*; 
import java.text.DecimalFormat; 
import java.util.Scanner; 

public class average { 
    public static void main(String[] args) { 

     Scanner keyboard = new Scanner(System.in); 
     int count = 0; 
     double ng = 0, total = 0, average; 
     int countt; 
     { 
     BufferedReader input = new BufferedReader (new InputStreamReader(System.in)); 
     } 
int max = 0; 
     while (ng > -1) { 
      if (ng > -1) 
      System.out.print("Enter your next grade (-1 to quit) : "); 
      ng = keyboard.nextDouble(); 
      total = total + ng; 
      count++; 
      max = ng > max? ng : max; 
     } 
     countt=count-1; 
     average = (total + 1)/countt; 
     System.out.println(" "); 
     System.out.println("Total number of students: " + countt); 
     System.out.println("Average of grades " + average); 
     System.out.println("Highest grade " + max); 

    } 
} 

Answer 2

循环之外，初始化一个新的变量分钟，Double.MAX_VALUE与Double.MIN_VALUE了新的变数最大。 在循环内部，如果ng大于max update max和ng。如果ng小于min，则用ng更新min。

Answer 3

您可以创建一个TreeSet，为其添加每个数字，然后简单地获取第一个和最后一个条目 - 这些是TreeSet排序后的最小和最大条目。

Set<Double> set = new TreeSet<>(); 

在while循环

，加上双：

set.add(ng); 

和while循环后，得到

Object[] sa = set.toArray(); 
System.out.println("min: " + sa[0]); 
System.out.println("max: " + sa[sa.length - 1]); 

Answer 4

这里有一个简单的方法，你可以做到这一点。请参阅评论以获得解释。

这个想法是添加两个新的变量，一个为最高等级，一个为最低等级。每次从键盘输入新值时，都会将输入的值与当前的最高值和最低值进行比较。如果新值高于最高值（或低于最低值），则将新值指定为新的最高/最低等级。

import java.text.NumberFormat; 
import java.io.*; 
import java.text.DecimalFormat; 
import java.util.Scanner; 

public class Average { 
    public static void main(String[] args) { 

     Scanner keyboard = new Scanner(System.in); 
     int count = 0; 
     double ng = 0, total = 0, average; 
     int countt; 

     // Add these variables 
     boolean firstRun = true; 
     double largest = 0; 
     double smallest = 0; 

     { 
      BufferedReader input = new BufferedReader (new InputStreamReader(System.in)); 
     } 
     while (ng > -1) { 
      if (ng > -1) 
       System.out.print("Enter your next grade (-1 to quit) : "); 
      ng = keyboard.nextDouble(); 

      // Add this part for calculating largest and smallest 
      if (ng > -1) { 
       // When you run it the first time, assign this first value as the largest and 
       // smallest value, since it is the only value you've seen at the moment 
       if (firstRun) { 
        firstRun = false; 
        largest = ng; 
        smallest = ng; 
       } else { // If it's not the first run, then compare the values 
        // Check if the current value is bigger than your current max value 
        if (ng > largest) { 
         largest = ng; 
        } 

        // Check if the current value is smaller than your current min value 
        if (ng < smallest) { 
         smallest = ng; 
        } 
       } 
      } 

      total = total + ng; 
      count++; 
     } 
     countt=count-1; 
     average = (total + 1)/countt; 
     System.out.println(" "); 
     System.out.println("Total number of students: " + countt); 
     System.out.println("Average of grades " + average); 

     // Et voila! 
     System.out.println("Highest grade " + largest); 
     System.out.println("Lowest grade " + smallest); 

    } 
} 

Answer 5

import java.text.NumberFormat; 
import java.io.*; 
import java.text.DecimalFormat; 
import java.util.Scanner; 

public class average { 
    public static void main(String[] args) { 

     Scanner keyboard = new Scanner(System.in); 
     int count = 0; 
     double ng = 0, total = 0, average, smallest = -1, largest = -1; 
     int countt; 
     { 
     BufferedReader input = new BufferedReader (new InputStreamReader(System.in)); 
     } 
     while (ng > -1) { 
      if (ng > -1) 
      System.out.print("Enter your next grade (-1 to quit) : "); 
      ng = keyboard.nextDouble(); 
      if (smallest == -1 || (ng != -1 && ng < smallest)) 
       smallest = ng; 
      if (ng > largest) 
       largest = ng; 
      total = total + ng; 
      count++; 
     } 
     countt=count-1; 
     average = (total + 1)/countt; 
     System.out.println(" "); 
     System.out.println("Total number of students: " + countt); 
     System.out.println("Average of grades " + average); 
     System.out.println("Highest grade " + ""); 
     System.out.println("largest: " + largest); 
     System.out.println("smallest: " + smallest); 

    } 
}