CODEWITHSUNDEEP
java
hbk
hbk

Reputation: 11184

get char from console and convert it to int

try to create new method, but during running it's not working code this placed on 

class Matrix {
    public static void main (String  args[]) throws IOException {
        ...
        System.out.println("Enter q-ty of matrix elements i= ");
        int gormatelement = 0;
        getchartoint (gormatelement);
        ...
    }
    ...
}

and after method

public static void getchartoint (int a) throws IOException{
    BufferedReader bReader = new BufferedReader (new InputStreamReader(System.in));
    String k = bReader.readLine();
    a =  Integer.parseInt(k);
}

this code must get char from console and convert it to int - will be used as q-ty of elements in matrix

Upvotes: 0

Views: 140

Answers (4)

qasfux
qasfux

Reputation: 207

You are assigning the result of of parseInt() to a, which is a local copy of "gormatelement" and which is deleted once the function ends. Java uses "call-by-value" for primitive data types.

You could also take a look at the Scanner Class:

public static int getIntFromCommandLine() {
    Scanner scan = new Scanner(System.in);
    return scan.nextInt();
}

Upvotes: 0

Lee Meador
Lee Meador

Reputation: 12985

When you change the value of a simple parameter variable (like a) inside a method, it does not change the variable that you gave when you called the method (like gormatelement).

The easiest way to do this is to have the method return the integer value and the calling code to store it.

int gormatelement = getchartoint ();

and

public static int getchartoint () throws IOException{
   int a;
   ... same code ...
   return a;
}

Expanded

If you want to go look up more about this concept of passing variables, you can Google the terms "call by value" and "call by reference".

Java uses a "call by value" but it is easy to get confused when objects with contained instance variables are passed to a method because the contained field values can be changed and the change seems to propagate to the object you called the method with.

What's happening is that the value of an Object is really a reference to the obect's contents, so to speak. You have to think about it a while to see what I mean.

Upvotes: 2

sr01853
sr01853

Reputation: 6121

public class x
{
public static void main(String[] args)
{
System.out.println("Enter q-ty of matrix elements i= ");
        int gormatelement = 0;
        getchartoint (gormatelement);
}

public static void getchartoint (int a) throws IOException{
            BufferedReader bReader = new BufferedReader (new 
                    InputStreamReader(System.in));
            String k = bReader.readLine();
                a =  Integer.parseInt(k);
            }
}

Since you are a beginner, At least this is required for your program to compile.

Upvotes: 1

Schnigges
Schnigges

Reputation: 1326

Try 

int gormatelement = YourClass.getchartoint(0);

Upvotes: -1

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