Question

Given the following code, how can I use myInt in private void jButton1 from private void jButton2?

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    int myInt = (Integer)jSpinner1.getValue();
}

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    int b = 0;
    int c = myInt;
    do {
        try {
            Object newInstance = Class.forName("com.mysql.jdbc.Driver").newInstance();
            Connection con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost/rk","root","root");
            PreparedStatement ps = (PreparedStatement) con.prepareStatement("INSERT INTO factors VALUES(?,?,?,?,?,?)");
            ps.setString(1,jTextField7.getText());
            ps.setString(2,jTextField8.getText());
            ps.setString(3,jTextField9.getText());
            ps.setString(4,jTextField10.getText());
            ps.setString(5,jTextField11.getText());
            ps.setString(6,jTextField12.getText());

            ps.executeUpdate();

            jTextField7.setText("");
            jTextField8.setText("");
            jTextField9.setText("");
            jTextField10.setText("");
            jTextField11.setText("");
            jTextField12.setText("");
        }
        catch (Exception e) {
            System.out.println(e);
        }

        b++;
    } while(b < my);
}

Answer 1

Variables are tied to a Variable Scope. In this case, myInt is declared in one method scope and you are then trying to access it from a different method scope. This is not possible.

To go around it, you will have to elevate the myInt variable to a Global (Class) variable, like so:

private int myInt;
...
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    this.myInt = (Integer)jSpinner1.getValue();
}
...

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
   int b = 0;
   int c= this.myInt;
...

The will mean that anything declared within the class scope will have access to this variable, meaning that your variable is now accessible from all your methods.