Why are both if and else statements being executed? Java

shouldn't the else-if statement execute if and only if the if statement is false?

However, the vector is empty and as I proceed to input the first elemnet, the first if statement works just fine, but then the else-if statement is executed and hangs in an infinite loop.

public void addProduct (Vector <Stock> temp){
    Scanner sc = new Scanner (System.in);
    sc.useDelimiter("\n");

    String name = "";
    String qty = "";
    String cost = "";
    int q = 0;
    int c = 0;
    boolean v;
    boolean added = false;
    Stock st = null;
    System.out.println("Enter Product Name: ");
    name = sc.next();

    do{
        if((name.matches(valn)) && (temp.size() == 0)){
            v = true;
            do{
                try{
                    System.out.println("Enter Quantity: ");
                    q = sc.nextInt();
                    System.out.println("Enter Cost: ");
                    c = sc.nextInt();
                    v = false;
                }catch(InputMismatchException ie){
                    sc.next();
                    System.out.println ("Invalid Entry!");
                }
            }while(v);
            qty = Integer.toString(q);
            cost = Integer.toString(c);
            Stock s1 = new Stock(name, qty, cost);
            temp.add(s1);
            added = true;
            System.out.println ("Product was Added Succesfully!");
            System.out.println ();
        }
        else if((name.matches(valn)) && (temp.size() > 0)){
            for(int i = 0; i < temp.size(); i ++){
                st = temp.elementAt(i);
                if(name == st.getName()){
                    System.out.println ("Product Already Exists."); 
                    System.out.println ();
                    System.out.println ("Note: Product will be Overwritten!");
                    v = true;
                    do{
                        try{
                            System.out.println("Enter Quantity: ");
                            q = sc.nextInt();
                            System.out.println("Enter Cost: ");
                            c = sc.nextInt();
                            v = false;
                        }catch(InputMismatchException ie){
                            sc.next();
                            System.out.println ("Invalid Entry! Please Try Again.");
                        }

                        if((qty.matches(valq)) && (cost.matches(valc))){
                            qty = Integer.toString(q);
                            cost = Integer.toString(c);
                            temp.elementAt(i).setQuantity(qty);
                            temp.elementAt(i).setCost(cost);
                        }
                    }while(v);
                    added = true;
                }
                System.out.println ();
            }
        }else
            System.out.println ("Invalid Name Input!");
    }while(added == true);
    System.out.println ();
}`