Convert object to String?

Question

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

Example:

        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));
            pessoaController.excluir(Integer.valueOf(codigo));
    }

Answer 1

First we need to differentiate conversion, which consists in transforming one type of data into another, one cast, which consists in accessing an object as a type more specific than the current reference allows.

Conversion

Converting one type of value into another requires a routine to process bytes or characters.

This reply considers that the conversion between number and text is done on basis 10.

Convert Integer to String

A variable of the 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 some external source, it may not contain a valid number. Therefore, it is important at all times treat the exception NumberFormatException, thus:

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

Cast

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

Example:

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

In the above example:

1. An object of the type Integer is created
2. It is stored in a variable of type Object
3. The cast (Integer) causes the type variable Object can be assigned to a variable of type Integer

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

If the actual type of the object was not compatible with Integer an exception ClassCastException would be launched at runtime. So it is always good to check whether the cast will be possible. Example:

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

In that case, no need to treat ClassCastException with try/catch, because instanceof guarantees that this will not occur.

Many Ides, like the Eclipse, will issue a warning (Warning) find a cast without a instanceof before.

Answer 2

Hello,

you can make a casting passing to the expected type, but it is good to make sure that the object is of the correct type.

int i = (Integer) object;

Font: stackoverflow

Answer 3

You can use the String.valueOf(int)

For example:

int par = 2;
String dois = String.valueOf(par);