nullpointer exception on android

Question

i just don't understand why I have a nullpointerexception with this:

public class MainActivity extends AppCompatActivity {

private EditText field;

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

    EditText field = (EditText) findViewById(R.id.field);
    Button plus = (Button) findViewById(R.id.plus);
    Button moins = (Button) findViewById(R.id.moins);
    Button ctof = (Button) findViewById(R.id.ctof);

    plus.setOnClickListener(buttonclick);
    moins.setOnClickListener(buttonclick);
    ctof.setOnClickListener(buttonclick);

}


private View.OnClickListener buttonclick = new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        switch(view.getId()){
            case R.id.plus:
                //TODO
                Toast.makeText(MainActivity.this, field.getText().toString(), Toast.LENGTH_LONG).show();
                break;
        }
    }
};


}

I don't understand my mistake, it's simple and I don't know where is the issue. I can't get my field and print the result.

probably one of the views you retrieved by `findViewById` is not in the `activity_main` layout or the name of it is different than those you used to get it. — Akram, Dec 26 '17 at 14:42
java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference at com.example.gon.tp03.MainActivity$1.onClick(MainActivity.java:38) — Userlambda, Dec 26 '17 at 14:43

Ege Kuzubasioglu · Accepted Answer · 2017-12-26T15:02:23.723

3

private EditText field;

You defined your edit text

and you've done it again

EditText field = (EditText) findViewById(R.id.field);

edited Dec 26 '17 at 15:02

answered Dec 26 '17 at 14:47

Ege Kuzubasioglu

5,991
12
49
85

yeah it was my mistake. it's work know. i forgot to delete the second definition. – Userlambda Dec 26 '17 at 14:49

score 1 · Answer 2 · answered Dec 26 '17 at 14:50

1

it's because you have declared your EditText twice. Remove "EditText" From "EditText field = ......" the problem will be solved

answered Dec 26 '17 at 14:50

Matin Gdz

217
2
13

nullpointer exception on android

2 Answers2