Question

I am trying to print value of a function variable in JSP Page. The function variable is located in java.class(com.project.bulk). File name is bulk.class. I tried reading the variable by writing below code in JSP file and it didn’t work. Any help please?

<%@ page import="com.project.bulk.bulk" %>

<%=bulk.cellStoreVector %>

// function code is below

private static void printCellDataToConsole(Vector dataHolder) {

            for (int i = 0; i < dataHolder.size(); i++) {
                    Vector  cellStoreVector  = (Vector) dataHolder.elementAt(i);
                    System.out.println(cellStoreVector);
                    for (int j = 0; j < cellStoreVector.size(); j++) {
                          HSSFCell myCell = (HSSFCell) cellStoreVector.elementAt(j);
                          String stringCellValue = myCell.toString();
                         // System.out.print(stringCellValue + "\t\t");
                    }
                    System.out.println();
            }
    }

Answer 1

You can’t access a local variable outside that method or the block in which it is defined. The scope of local variable is confined in the block where it is defined.

Your below declaration is local to the for-loop in which it is declared. Even in the current method, it will not be accessible outside the for-loop. Because your loop defined a scope of access for this variable: –

Vector  cellStoreVector  = (Vector) dataHolder.elementAt(i);

To access it in a JSP outside your class, declare that field as a private instance variable in your class. And have a public accessor method, that will return the value of that field. Then in your JSP, you can invoke that method to get the value for a particular instance.

Remember, you need to access that method on an instance of your class. You are accessing here directly through your class name. If you want to access it like that, you need a static variable.

Here’s a simple example covering what all I said above: –

public class Dog {

    // Private Instance variable
    private int instanceVar; // Defaulted to 0

    // Private Static variable
    // Common for all instances
    private static String name = "rohit";


    // Public accessor
    public int getInstanceVar() {
        return this.instanceVar;
    }

    public void setInstanceVar(int instanceVar) {
        this.instanceVar = instanceVar;
    }

    // Static public accessor for static variable
    public static String getName() {
        return name;
    }

}

class Test {
    public static void main(String[] args) {
        // Access static method through class name
        System.out.println(Dog.getName()); 

        Dog dog = new Dog();

        // Set instance variable through public accessor, on a particular instance
        dog.setInstanceVar(10);

        // Get instance variable value and asssign to local variable x
        // x is local variable in `main`
        int x = dog.getInstanceVar(); 

        showX(); 
    }

    public static void showX() {

        // x not visible here.
        System.out.println(x);  // Will not compile
    }
}