Convert object to String?

Question

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?

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));
    }

6

java string conversão-de-tipo

Author: Igor Contini, 2015-10-22

Source

3 answers

Hello,

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

int i = (Integer) object;

Font: stackoverflow

4

Author: Marco Souza, 2017-05-23 12:37:23

You can use String.valueOf(int)

For example:

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

-1

Author: António Macave, 2016-11-14 16:41:33

score 7 · Accepted Answer

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

Conversion

Converting one type of value to another requires a routine that does the processing of the bytes or characters.

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

Converter Integer for 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 some external source, it may not contain a valid number. So it's important always to treat the exception NumberFormatException like this:

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

Cast

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

Example:

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
or cast (Integer) causes the variable of type Object to be assigned to a variable of type Integer

Note that the cast it 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 thrown at runtime. So it's always good to check if the cast will be possible. Example:

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

In this case, one does not need to treat ClassCastException with try/catch, because instanceof guarantees that this will not occur.

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