How Can I initialize my variables from another layout?

Question

After much research, I have been unable to figure out how I can initialize my TextView in my java file in Android Studio. The TextView in question is located in a different layout file so I don't know the correct syntax to use. I think my question is similar to: Null pointer Exception on .setOnClickListener But the solution for him is not working for me. Here is my troublesome code:

 Microsoft = (Button) findViewById(R.id.Microsoft);
        Microsoft.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

                //TextView score = (TextView) findViewById(R.id.score);
                TextView score = (TextView) 
score.findViewById(R.id.question2);
                (score).setText(0);

            }
        });

TheFindViewById part is the part I need.

FULL CODE VVVV

package org.flinthill.finalprojectv3;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.view.View.OnClickListener;
import android.widget.Toast;
import android.text.method.DigitsKeyListener;
import android.text.InputFilter;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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

    Button SuSe;
    Button DOS;
    Button B;
    Button BIOS;
    Button Microsoft;
    Button LenBosackandSandyLerner;
    Button HaskelDiklah;
    Button SteveWozniak;

    SuSe = (Button) findViewById(R.id.SuSe);
    SuSe.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText(0);

        }
    });
    DOS = (Button) findViewById(R.id.DOS);
    DOS.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText("0");

        }
    });

    B = (Button) findViewById(R.id.B);
    B.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText("0");

        }
    });
    BIOS = (Button) findViewById(R.id.BIOS);
    BIOS.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Right!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText("1");

            setContentView(R.layout.question2);

        }
    });

    //QUESTION 2

    Microsoft = (Button) findViewById(R.id.Microsoft);
    Microsoft.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

            //TextView score = (TextView) findViewById(R.id.score);
            TextView score = (TextView) 
score.findViewById(R.id.question2);
            (score).setText(0);

        }
    });
    /*LenBosackandSandyLerner = (Button) 
findViewById(R.id.LenBosackandSandyLerner);
    LenBosackandSandyLerner.setOnClickListener(new 
View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Right!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText("2");

            setContentView(R.layout.question3);

        }
    });

    HaskelDiklah = (Button) findViewById(R.id.HaskelDiklah);
    HaskelDiklah.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText("0");

        }
    });
    SteveWozniak = (Button) findViewById(R.id.SteveWozniak);
    SteveWozniak.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Toast.makeText(getApplicationContext(), "Wrong!", 
Toast.LENGTH_SHORT).show();

            TextView score = (TextView) findViewById(R.id.score);
            (score).setText("0");

        }
    });*/

}

}

XML CODE:

LAYOUT 1:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="@drawable/android"
tools:context="org.flinthill.finalprojectv3.MainActivity">

<TextView
    android:layout_width="wrap_content"
    android:id="@+id/LUL"
    android:textColor="@color/LightGreen"
    android:layout_height="wrap_content"
    android:typeface="serif"
    android:text="Which is NOT an OS?"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="32dp"
    android:textSize="24sp"/>

<Button
    android:id="@+id/SuSe"
    android:onClick="SuSeClick"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="SuSe"
    android:layout_marginTop="100dp"
    android:layout_below="@+id/LUL"
    android:layout_centerHorizontal="true" />

<Button
    android:id="@+id/BIOS"
    android:onClick="BIOSClick"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="BIOS"
    android:layout_below="@+id/SuSe"
    android:layout_centerHorizontal="true" />

<Button
    android:id="@+id/DOS"
    android:onClick="DOSClick"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="DOS"
    android:layout_below="@+id/BIOS"
    android:layout_centerHorizontal="true" />

<Button
    android:id="@+id/B"
    android:onClick="BClick"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="B"
    android:layout_below="@+id/DOS"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/score"
    android:textColor="@color/colorAccent"
    android:text="0"
    android:textSize="32dp"
    android:layout_below="@+id/LUL"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="33dp" />
</RelativeLayout>

LAYOUT 2:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/question2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="@drawable/android"
tools:context="org.flinthill.finalprojectv3.MainActivity">

<TextView
    android:layout_width="wrap_content"
    android:id="@+id/question2text"
    android:textColor="@color/LightGreen"
    android:layout_height="wrap_content"
    android:typeface="serif"
    android:text="Who created Cisco"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="32dp"
    android:textSize="24sp"/>

<Button
    android:id="@+id/Microsoft"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Microsoft"
    android:layout_marginTop="100dp"
    android:layout_below="@+id/question2text"
    android:layout_centerHorizontal="true" />

<Button
    android:id="@+id/LenBosackandSandyLerner"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Len Bosack and Sandy Lerner"
    android:layout_below="@+id/Microsoft"
    android:layout_centerHorizontal="true" />

<Button
    android:id="@+id/HaskelDiklah"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Haskel Diklah"
    android:layout_below="@+id/LenBosackandSandyLerner"
    android:layout_centerHorizontal="true" />

<Button
    android:id="@+id/SteveWozniak"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Steve Wozniak"
    android:layout_below="@+id/HaskelDiklah"
    android:layout_centerHorizontal="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/score"
    android:textColor="@color/colorAccent"
    android:text="1"
    android:textSize="32dp"
    android:layout_below="@+id/question2text"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="33dp" />
</RelativeLayout>

what you wanna achieve? set 0 to textview while clicking on button? — Ali Ahsan, May 22 '17 at 12:25
Well, where does `R.id.score` exist? Did you you add it to the exact same xml file as those buttons? — OneCricketeer, May 22 '17 at 12:26
If you're getting a nullpointerexception on the button setOnClickListener, then you're using the wrong layout. — OneCricketeer, May 22 '17 at 12:28
Yes I would like the TextView to be set to "0" when clicking the button, R.id.score exists in the xml file called "question2"... Holy crap... why did this get so many downvotes? :( — KamehK, May 22 '17 at 12:28
Please see about creating a [mcve] and add your xml and the rest of the Activity code — OneCricketeer, May 22 '17 at 12:29
and you are inflating same layout question2 for this activity/fragment? & Microsoft button also in question2 layout? — Ali Ahsan, May 22 '17 at 12:32
I am using one java file to code for two layouts basically. And yes, Microsoft button is in the layout "question2" — KamehK, May 22 '17 at 12:45

Luiz Fernando Salvaterra · Answer 1 · 2017-05-22T12:32:13.487

0

You cannot do this unless your TextView is within the layout your Activity, Fragment or Dialog controls.

The findViewById method looks for Views within the layout previously configured by the setContentView(layout) or the layout inflated in your Fragment or Dialog. If it does not find anything, your TextView will have a null reference.

edited May 22 '17 at 12:32

answered May 22 '17 at 12:27

Luiz Fernando Salvaterra

4,192
2
24
42

The question is about the TextView, I believe, not the button – OneCricketeer May 22 '17 at 12:31
Are you sure there is no other way to do it? In the link above, it appears someone figured out how to do it... Even though it sill didn't work for me it apparently worked for him. – KamehK May 22 '17 at 12:31
can you put your xml file here? – Luiz Fernando Salvaterra May 22 '17 at 12:33
xml files were added to the original post – KamehK May 22 '17 at 12:46

score 0 · Accepted Answer · answered May 22 '17 at 12:32

0

   //Change the name id in the xml file
   Button microsoftButton = (Button) findViewById(R.id.microsoftButton);
   TextView scoreTextView = (TextView) findViewById(R.id.scoreTextView);

       microsoftButton.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               Toast.makeText(getApplicationContext(),"Wrong!", Toast.LENGTH_SHORT).show();

               // This was declared above so now you can use it. You can only set it to a String not to an Integer.
               scoreTextView.setText("0");

          }
       });

answered May 22 '17 at 12:32

fsebek

389
2
9

You have three options. 1. You inflate it using the inflator service. 2. You create a custom button with extends the standard Button class. 3. You can include external xml files into the activities xml by using – fsebek May 22 '17 at 12:44
I will try inflating it. Thanks. – KamehK May 22 '17 at 14:33
Remember that after inflating you need to add it as well! – fsebek May 22 '17 at 14:55

How Can I initialize my variables from another layout?

2 Answers2