String comparison problem [duplicate]

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String comparison problem [duplicate]

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#1 by (4 votes)
#2 by (1 votes)

0

I need to compare if the name entered in the textField is the same as the "root" user. When comparing even by typing root Eclipse informs you that it is invalid. Unfortunately I do not understand the reason for the error.

// ...
            model.Usuario mUser = new Usuario();

            // Enviar Usuario e Senha
            String tfUser = tfUsuario.getText().toString().trim();
            char[] tfPassword = tfSenha.getPassword();
            mUser.setUser(tfUser);
            mUser.setPassword(tfPassword);

            // ...
            if(tfUsuario.getText() == "root") {
                JOptionPane.showMessageDialog(null, "Válido", "Aviso", 0);
                System.out.print(tfUsuario.getText());
            } else if(tfUsuario.getText() != "root") {
                JOptionPane.showMessageDialog(null, "Inválido", "Aviso", 0);
                System.out.print("Nome do Usuário: " + tfUsuario.getText());
            }

java string

asked by anonymous 11.06.2018 / 14:01

2 answers

1

Always use equals() when comparing Strings .

Using == causes confusion of this type:

String nome1 = new String("Marcela");
String nome2 = new String("Marcela");

System.out.println(nome1 == nome2); //false

String nome3 = "Marcela";
String nome4 = "Marcela";

System.out.println(nome3 == nome4); //true

11.06.2018 / 14:42

Why does .all in an empty list return true? More than one value in the same GET parameter

score 4 · Accepted Answer

4

Use the equals() method to compare Strings in Java. As the String in java is an object, when you use == compares the object's memory address:

Ex:

if("texto1".equals("texto2")){

}

11.06.2018 / 14:05