#Help. Java code, getting the marks of 5 students and displaying the students who got A using Arrays method

Question

I have a problem. I am tasked to write a Java program, using the array method, that receives the marks of 5 students, and then finds and displays the number of students getting A grade. The marks are (60,56,78,99,92.5). The criteria needed to get grade A is 80 marks and above.

Everything in my code went well, except for the last statement: System.out.println("The number of students "+count);

This is my code:

import javax.swing.JOptionPane;

public class Q2 {

 public static void main(String [] args) {

    double[] marks = new double[6];
    int numbers = 1;

    // This is for asking input
    for (int i = 0; i < marks.length; i++,numbers++) {
        String marksString = JOptionPane.showInputDialog (null,
                "Enter the marks for student "+numbers+": ");

        marks[i] = Double.parseDouble(marksString);

        int count = 0;
        if(marks[i] >= 80.0) {
            count++;
        }
    }
    System.out.println("The number of students "+count); 
 }

}

Everything in my code went well, except for the last statement: System.out.println("The number of students "+count);

I received an error:

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous tree type:

Is there anyone who can explain and correct my mistakes? :D

Possible duplicate of [Cannot find symbol while loop](https://stackoverflow.com/questions/19044573/cannot-find-symbol-while-loop) — BackSlash, Jun 25 '17 at 09:40
Possible duplicate of [java.lang.RuntimeException: Uncompilable source code - what can cause this?](https://stackoverflow.com/questions/2333285/java-lang-runtimeexception-uncompilable-source-code-what-can-cause-this) — Joe C, Jun 25 '17 at 09:40
Also: ['Cannot Find Symbol' error when using a 'for' loop](https://stackoverflow.com/questions/10454345/cannot-find-symbol-error-when-using-a-for-loop) — BackSlash, Jun 25 '17 at 09:41

Eran · Accepted Answer · 2017-06-25T09:47:21.800

You wrongly declared count inside the for loop. As a result, it is not accessible outside the loop (hence the compilation error), and in addition, it's overwritten to 0 in each iteration of the loop, which means it will always have a value of 0 or 1 (before exiting the loop), instead of the correct count.

Move it outside the loop:

double[] marks = new double[6];
int numbers = 1;
int count = 0;
// This is for asking input
for (int i = 0; i < marks.length; i++,numbers++) {
  String marksString = JOptionPane.showInputDialog (null,
      "Enter the marks for student "+numbers+": ");
  marks[i] = Double.parseDouble(marksString);
  if(marks[i] >= 80.0) {
    count++;
  }
}
System.out.println("The number of students who got A is " + count);

*"The number of students "+count* -> *"The number of students who got A: "+count*... — Am_I_Helpful, Jun 25 '17 at 09:45

score 0 · Answer 2 · answered Jun 25 '17 at 09:53

public class Q2 {

public static void main(String [] args) {

double[] marks = new double[6];
int numbers = 1;
int count = 0;

// This is for asking input
for (int i = 0; i < marks.length; i++,numbers++) {
    String marksString = JOptionPane.showInputDialog (null,
            "Enter the marks for student "+numbers+": ");

    marks[i] = Double.parseDouble(marksString);

    if(marks[i] >= 80.0) {
        count++;
    }
}
System.out.println("The number of students "+count); 
}

}

Your mistake is that you initialize the count inside the loop, and over each iteration, the compiler assigns the value 0 to your count. Put it above the loop.

score 0 · Answer 3 · answered Jun 25 '17 at 17:42

You have declared and initialized the count variable inside the loop.As a result you will unable to get access to the count variable outside that for loop.And each time when the loop goes on count variable will assign to 0.Those are the two errors that you have been done.

import javax.swing.JOptionPane;

public class Demo {

public static void main(String [] args) {

double[] marks = new double[6];
int numbers = 1;
int count=0;
// This is for asking input
for (int i = 0; i < marks.length; i++,numbers++) {
    String marksString = JOptionPane.showInputDialog (null,
            "Enter the marks for student "+numbers+": ");

    marks[i] = Double.parseDouble(marksString);

    //int count = 0;
    if(marks[i] >= 80.0) {
        count++;
    }
  }
 System.out.println("The number of students "+count); 
 }

  }

You should declare the count variable outside the for loop.

#Help. Java code, getting the marks of 5 students and displaying the students who got A using Arrays method

3 Answers3