Simple Interest Calculation using jframe(Java GUI)

Write a Java program to calculate a simple interest. This program must be focused on an object oriented approach.

video tutorial link: video

N.B. : Java source code is case sensitive
Source code:  java_simple_interest . java

package java_simple_interest;
//class
class simple_interest
{
    //instance variable
    float principal_amount;
    float year_of_interest;
    float rate_of_interest;
    //method with arguments and return type
    float si(float pa, float yi, float ri)
    {
        return pa*yi*ri;
    }
}

Source Code: calculate_simple_interest . java

(Source code under action button ( jButton1 ))

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
       
 // TODO add your handling code here:
        //create object
        simple_interest si =new simple_interest();
        //instance variable getting value from text box
        si.year_of_interest=Float.parseFloat(yoi.getText());
        si.rate_of_interest=Float.parseFloat(roi.getText());
        si.principal_amount=Float.parseFloat(pa.getText());
        //method si called by object si
        jLabel4.setText ("Your Payable interest  is: " + si.si(si.year_of_interest,si.rate_of_interest ,si.principal_amount ));
       
    }