java.lang.NullPointerException: Attempt to invoke virtual method 'setOnClickListener' on a null object reference

Question

I may have some troubles finding where the problem is ... Here is my activity_main.xml :

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.grasland.test.MainActivity">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/poids"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:text="@string/poids"
            android:textColor="#FF0000"
            android:textStyle="bold"
            android:textSize="20sp" />

        <EditText
            android:id="@+id/editPoids"
            android:layout_width="match_parent"
            android:layout_height="50sp"
            android:layout_below="@id/poids"
            android:hint="@string/editPoids"
            android:inputType="number"/>

        <TextView
            android:id="@+id/taille"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/editPoids"
            android:layout_centerHorizontal="true"
            android:text="@string/taille"
            android:textColor="#FF0000"
            android:textStyle="bold"
            android:textSize="20sp" />

        <EditText
            android:id="@+id/editTaille"
            android:layout_width="match_parent"
            android:layout_height="50sp"
            android:layout_below="@id/taille"
            android:hint="@string/editTaille"
            android:inputType="number"/>

        <RadioGroup
            android:id="@+id/radioGroup1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:orientation="horizontal"
            android:layout_below="@id/editTaille">

            <RadioButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/radioButtonCm"
                android:checked="true" />

            <RadioButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/radioButtonM"/>
        </RadioGroup>

        <Button
            android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/radioGroup1"
            android:text="@string/button"/>

        <TextView
            android:id="@+id/resultTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/button"
            android:paddingTop="40dp"
            android:layout_centerHorizontal="true"
            android:text="@string/resultTitle"
            android:textSize="20sp" />

        <TextView
            android:id="@+id/result"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@id/resultTitle"
            android:paddingTop="20dp"
            android:layout_centerHorizontal="true"
            android:textSize="80sp" />

    </RelativeLayout>


</FrameLayout>

and there is my java file :

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

    public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Button calculImc = (Button) findViewById(R.id.button);
        final EditText poidsView = (EditText) findViewById(R.id.editPoids);
        final EditText tailleView = (EditText) findViewById(R.id.editTaille);
        final TextView resultat = (TextView) findViewById(R.id.result);
        calculImc.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int iPoids = Integer.parseInt(poidsView.getText().toString());
                int iTaille = Integer.parseInt(tailleView.getText().toString());
                double dResult = iPoids / ( ( iTaille * iTaille ) / 1000 );
                resultat.setText(Double.toString(dResult));
            }
        });
    }
}

I can't see the reason for this NullPointerException I'm getting (I may be a bit tired ...).

Thanks in advance !

Sylvain.

score 1 · Accepted Answer · answered Dec 26 '16 at 22:51

I don't see you placing the setContentView function below onCreate

You should consider doing:

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

java.lang.NullPointerException: Attempt to invoke virtual method 'setOnClickListener' on a null object reference

1 Answers1