使用 JOptionPane [关闭] 查找数组中的最高和最低数字

Question

the code it's for education in college I need the user to insert a values of array and find which number is the highest and lowest but the lowest number doesn't work . can anyone explain this to me , sorry for asking much

int m=Integer.parseInt(JOptionPane.showInputDialog("Enter index"));       
int values;
int num [] = new int [m];

int max = num[0];
int min = num[0];
for (int i=0;i<num.length;i++)      
     {                          
     num[i] = values =Integer.parseInt(JOptionPane.showInputDialog("Enter value"));   
     System.out.println(num[i]);

     if (num[i] > max)
     {
         max=num[i];
     }
     if (num[i] < min )
     {
         min=num[i];
     }

}                                    
System.out.println("Largest Number in a given array is : " + max);
System.out.println("Smallest Number in a given array is : " + min);

Answer 1

Welcome,

int[] num= new int[4];

After initialize num, num will be {0, 0, 0, 0};

int max = num[0];
int min = num[0];

So now min will be 0, because num[0] is 0 - no matter what you enter.

num[i] = values =Integer.parseInt(JOptionPane.showInputDialog("Enter value"));   
System.out.println(num[i]);
if(i == 0)
      min = num[i];

Try this and think about it (same for max value)

Answer 2

You can use Arrays.sort() to sort the array and simply access the first(0th) index which will hold the smallest number, and the last index which will hold the largest number:

int m=Integer.parseInt(JOptionPane.showInputDialog("Enter index"));       
 //int values; dont need this
 int num [] = new int [m]; //num is initialised with length entered by the user

 //int max = num[0]; no need
 //int min = num[0]; no need
 for (int i=0;i<num.length;i++)      
 {                          
  num[i] = Integer.parseInt(JOptionPane.showInputDialog("Enter value"));   
  System.out.println(num[i]);      

 }
Arrays.sort(num); //this will sort your array in ascending order: smallest number will be at the 0th index and largest will be at the last index                                    
System.out.println("Largest Number in a given array is : " + num[num.length-1]);
System.out.println("Smallest Number in a given array is : " + num[0]);

Answer 3

There are a few errors in your code - so using your attempt, you can set the first value after it's been received from the user as the min and max, and work from there:

int m = Integer.parseInt(JOptionPane.showInputDialog("Enter index"));
int num[] = new int[m];
int max = Integer.parseInt(JOptionPane.showInputDialog("Enter value"));
System.out.println(max);
int min = max;
for (int i = 0; i < num.length - 1; i++) {
    num[i] = Integer.parseInt(JOptionPane.showInputDialog("Enter value"));
    System.out.println(num[i]);
    if (num[i] > max) {
        max = num[i];
    } else if (num[i] < min) {
        min = num[i];
    }
}
System.out.println("Largest Number in a given array is : " + max);
System.out.println("Smallest Number in a given array is : " + min);

---

With 5 inputs of 3, 8, 6, 4 and -33, the output is:

Largest Number in a given array is : 8

Smallest Number in a given array is : -33

---

Just for fun, here's an alternative solution that's quite inefficient:

System.out.println(Arrays.stream(num).boxed().mapToInt(Integer::intValue).max().getAsInt());
System.out.println(Arrays.stream(num).boxed().mapToInt(Integer::intValue).min().getAsInt());

Or of course you could sort the array with Arrays.sort() and then find the max with array[array.length() - 1] and the min with array[0]

Answer 4

You can use the Integer.MAX_VALUE and Integer_MIN_VALUE . max value for an integer is 2147483647(2^31-1) and min value for an integer is -2147483648(-2^31)

int m=Integer.parseInt(JOptionPane.showInputDialog("Enter index"));       
int num [] = new int [m];
int max = Integer.MAX_VALUE;
int min = Integer.MIN_VALUE;

 for (int i=0;i<num.length;i++)      
 {                          
     num[i] = values =Integer.parseInt(JOptionPane.showInputDialog("Enter value"));   
     System.out.println(num[i]);
     if (num[i] > max)
     {
         max=num[i];
     }
     if (num[i] < min )
     {
         min=num[i];
     }
}  

Hope this works for you.