java - How to handle invalid input when using Scanner.nextInt() -

i beginner , wrote java program allows enter n numbers , displays max, min , average if number -5 entered, program not displaying correctly , need help. want use try/catch catch errors when string entered instead integer.

        import java.util.scanner; public class average{ public static void main(string[]args){  system.out.print("enter integer numbers or -5 quit:");         scanner scan =new scanner(system.in);     double avg = 0.0;     int number = -1;     double avg = 0.0;     double sum = 0;     int count = 0;      int min = integer.max_value;     int max = integer.min_value;      try {     while((scan.nextint())!= -5)        {      if (count != 0) {         avg = ((double) sum) / count;     count++;     }             if (number > max){         max = number;         }         if(number < min){        min = number;         }         catch (inputmismatchexception e) {       system.out.println("please enter integer numbers");      system.out.println("average : " + avg);      system.out.println("maximum : " + max);     system.out.println("minimum : " + min); } } } } } 

you want

if(number > max) {     max = number; } if(number < min) {     min = number; } 

inside while loop because right checking last read value(also, there's no need counter outisde loop(after have read -5, btw, why -5?o.o).

also, want min/max values initialised way, because if min value bigger 0, code outputs 0. same goes if max value below 0:

int min = integer.max_value; int max = integer.min_value; 

for non-integer part: read on exceptions , use try-catch block catch inputmismatchexception.

try {     //while(scan.nextint) here } catch (inputmismatchexception e) {     //do here, print in console } 

as else pointed out, if want average not truncated, cast sum double: ((double) sum) / count.

finally, important: try debugging before asking else.