Convert object to String?


What is the best way to convert an object to a variable of type int ? Or is there no such conversion?


        if (teste == JOptionPane.OK_OPTION) {
            int linha = tblPessoa.getSelectedRow();

            // Aqui o objeto não pode ser convertido em string.
            int codigo = Integer.parseInt(tblPessoa.getModel().getValueAt(linha, 0));
asked by anonymous 22.10.2015 / 14:50

3 answers


First you need to differentiate conversion , which is to transform one data type into another, from a cast , which consists of accessing an object as a more specific type of which the current reference allows.


Converting one value type to another requires a routine that processes bytes or characters.

This answer considers that the conversion between number and text is done in base 10.

Convert Integer to String

A variable of type Integer

String str = myInteger.toString();

Primitive integer:

String str = Integer.toString(123, 10); //base 10    

Convert String to Integer

The command is simple:

Integer inteiro = Integer.valueOf("1");

Or if you want the primitive value:

int inteiro = Integer.parseInt("1");

The problem is that if the String is typed or read from an external source, it may not contain a valid number. So it is important always to handle the exception NumberFormatException , like this:

try {
    int inteiro = Integer.parseInt(stringDuvidosa);
} catch (NumberFormatException e) {
    //log, mensagem de erro, etc.


If you have an object of a specific type referenced as a generic type, you can do a cast to access it again as the specific type.


Object objeto = Integer.valueOf(1);
Integer inteiro = (Integer) objeto;

In the example above:

  • An object of type Integer is created
  • It is stored in a variable of type Object
  • The cast (Integer) causes the variable of type Object to be assigned to a variable of type Integer

    Note that cast does not modify the object in any way, just the way it is referenced.

    If the actual object type was not compatible with Integer a ClassCastException exception would be thrown at runtime. So it's always good to check if cast is possible. Example:

    Object objeto = ...
    if (objeto instanceof Integer) {
        Integer inteiro = (Integer) objeto;
    } else {
        //log, erro, etc.

    In this case, you do not have to treat ClassCastException with try/catch , because instanceof ensures that this will not happen.

    Many IDEs, such as Eclipse, will issue a warning if they find a cast without a instanceof before.

    12.11.2015 / 06:23


    You can do a casting by going to the expected type, but it's good to make sure the object is of the correct type.

    int i = (Integer) object;

    Font: stackoverflow

    22.10.2015 / 14:58

    You can use String.valueOf(int)

    For example:

    int par = 2;
    String dois = String.valueOf(par);
    14.11.2016 / 17:21