Double.valueOf(String). doubleValue()

Question

Since I could not convert a String to Double, because it is decimal, I used Double.valueOf(String). doubleValue(). But when converting a String to Double with "." the numbers above 3 houses (1,000) are not stored in Double variable even with the above code, only numbers smaller than (1,000) are stored. How do I convert a String to decimal for calculations? ->Formatted field for monetary values.

    Double vlprod=0.0;
    ArrayList<String> valorUnitario = new ArrayList();
    ArrayList<String> quantidade = new ArrayList();
     if (lstProduto.isSelectionEmpty()) /*Verifica se foi selecionado um item na JList*/
           { 
               JOptionPane.showMessageDialog(null, "Selecione um item na lista de produtos !");
           }
           else /*Se foi selecionado, pega o valor na posição do ArrayList referente ao índice da JList*/
           {
                int i= lstProduto.getSelectedIndex();
                Double vl=Double.valueOf(valorUnitario.get(i)).doubleValue();
                int qt=Integer.parseInt(quantidade.get(i));
                vlprod=Double.valueOf(vlprod+(vl*qt)).doubleValue();
                System.out.println(vlprod.toString());
           }

Erro no Console: Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: multiple points
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1914)
    at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
    at java.lang.Double.parseDouble(Double.java:538)

Answer 1

In float and double types, by default, the point(.) is decimal separator, not thousands separator. If your string uses point as thousands separator, you won’t be able to convert properly to double, not before applying some type of formatting or removing these separators.

If you’re sure that the point will always be just thousands separator, simply remove it from the string before converting:

    String str = "1.000";   
    System.out.println(Double.parseDouble(str.replaceAll("\\.", "")));

See working: https://ideone.com/f6u5h2

If you cannot guarantee this, edit the question and present examples of the types of numbers that may occur in your application.

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