Add value to a selected jlist model

Question

So I am trying to make a program that adds a subject to a jList from a textfield and after that, I want to add the grade for that subject from a textfield. Is it possible to store (in an array) that value to the item selected on the jList? so that I can access it for getting the average of all the grades of the subjects entered.

int x[] = jList1.getSelectedIndices();
    for(int i = 0; i < jList1.getModel().getSize(); i++){
        grade[x[i]] = Double.parseDouble(jTextField2.getText());
        jList1.getSelectedValue();
    }

Answer 1

You are supposed to manipulate data in the model that jList is based on.

listModel = new DefaultListModel();
listModel.addElement("Jane Doe");
listModel.addElement("John Smith");
listModel.addElement("Kathy Green");

list = new JList(listModel);

https://docs.oracle.com/javase/tutorial/uiswing/components/list.html#creating

Jlist is a (view) component that displays a list of objects and allows the user to select one or more items. A separate model, ListModel, maintains the contents of the list.

https://docs.oracle.com/javase/8/docs/api/javax/swing/JList.html

What is the exact problem with your implementation?

EDIT

    Double grade = Double.parseDouble(jTextField2.getText());            
    for(int i = 0; i < jList1.getModel().getSize(); i++){
        String before = jList1.getModel().getElementAt(i);
        String after=before+"_"+String.valueOf(grade);
        jList1.getModel().setElementAt(after,i);
    }

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