Problem in making Textview display updated value

Question

I’m making a simple application, it’s just a counter, with two buttons, "+"e"-", which consists of displaying an initial value of 0, and if I click any of the buttons, the value displayed on the screen will be added, or decremented, according to the corresponding button. My problem is in displaying the new value on the screen. I take the value of Textview, make the changes, and finally, I can’t display it on the screen, the app just closes.

 public class MainActivity extends AppCompatActivity {

Button btmais, btmenos, btmais2, btmenos2 ;
TextView pontuacao, pontuacao2;
EditText nome, nome2;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btmais = (Button) findViewById(R.id.btmais);
    btmenos = (Button) findViewById(R.id.btmenos);
    btmais2 = (Button) findViewById(R.id.btmais2);
    btmenos2 = (Button) findViewById(R.id.btmenos2);

    pontuacao = (TextView) findViewById(R.id.pontuacao);
    pontuacao2 = (TextView) findViewById(R.id.pontuacao2);

    btmais.setOnClickListener(new View.OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            int numero = Integer.parseInt( pontuacao.getText().toString() );
            numero = numero + 1;
            pontuacao.setText(numero);
        }
    });
}

}

Xml codes:

<TableLayout
    android:layout_width="182dp"
    android:layout_height="match_parent">

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <EditText
            android:id="@+id/nome"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="Name" />

    </TableRow>

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/pontuacao"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAlignment="center"
            android:textSize="100sp"
            tools:text="00" />
    </TableRow>

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <Button
            android:id="@+id/btmais"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="+" />

    </TableRow>

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <Button
            android:id="@+id/btmenos"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="-" />

    </TableRow>

</TableLayout>

<TableLayout
    android:layout_width="wrap_content"
    android:layout_height="match_parent">

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <EditText
            android:id="@+id/nome2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="Name" />

    </TableRow>

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/pontuacao2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="01"
            android:textAlignment="center"
            android:textSize="100sp"
            tools:text="@string/pontuacao2" />
    </TableRow>

    <TableRow
        android:layout_width="wrap_content"
        android:layout_height="match_parent">

        <Button
            android:id="@+id/btmais2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="+" />

    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/btmenos2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="-" />
    </TableRow>

</TableLayout>

Many components of the layout are still in disuse because I first need to make this code work, it is the main part.

Thank you very much for your help and attention

Answer 1

First you have to declare the variable numero globally outside the Initiating button with 0.

private int numero = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btmais.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v)
        {
            numero++;
        }
    });
}

Ai then do not insert an integer value directly into the method setText(). Use the static method valueOf to convert first to string. See how it should look:

pontuacao.setText(String.valueOf(numero));

See the final result:

final int numero = 0;
btmais.setOnClickListener(new View.OnClickListener()
{
    @Override
    public void onClick(View v)
    {
        numero++;
        pontuacao.setText(String.valueOf(numero));
    }
});

You can also use the method toString(). Look at this question what is the difference between using Object.toString() and String.valueOf()?