How can I enter a variable on a ResultSet Execute Query Where clause?

This is the Query I need to put a variable on the Where clause. Variable is itemnamestr that will be entered by the user.
rs = stmt.executeQuery("SELECT itemid, itemname FROM inventorytable WHERE itemname = itemnamestr ");
I got this error when putting itemnamestr as variable on SQL Where clause

Got an exception!
Unknown column 'itemnamestr' in 'where clause'

How can I correctly do it?

import java.sql.*; 
import javax.swing.*;
public class NewClass {
    
 
  
    public static void main (String[] args) { 
        String itemnamestr;
        
        itemnamestr = JOptionPane.showInputDialog(null, "Enter item name.");
 
        try { 
            String url = "jdbc:mysql://localhost:3306/test1"; 
            Connection conn = DriverManager.getConnection(url,"root","mypassword"); 
            Statement stmt = conn.createStatement(); 
            ResultSet rs; 
  
            rs = stmt.executeQuery("SELECT itemid, itemname FROM inventorytable WHERE itemname = itemnamestr "); 
            while ( rs.next() ) { 
                String itemidvar = rs.getString("itemid"); 
                System.out.println(itemidvar); 
                String itemnamevar = rs.getString("itemname"); 
                System.out.println(itemnamevar); 
            } 
            conn.close(); 
        } catch (Exception e) { 
            System.err.println("Got an exception! "); 
            System.err.println(e.getMessage()); 
        } 
    } 
}

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