Why doesn't my textview display anything?

Question

im currently doing a app that has a barcode scanner. currently when i scanned the barcode it is suppose to display the format of the barcode and the contents also. but currently it doesnt display the format and contents after scanning.

here is the code

public class ThreeFragment extends Fragment{

    public ThreeFragment() {
        // Required empty public constructor
    }

    Button scan_btn;
    EditText Edit_current;
    TextView formatTxt, contentTxt;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle   savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_one, container, false);
        scan_btn = (Button) view.findViewById(R.id.scan_button);
        final Activity activity = getActivity();
        scan_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                IntentIntegrator integrator = new IntentIntegrator(activity);
                integrator.setDesiredBarcodeFormats(IntentIntegrator.PRODUCT_CODE_TYPES);
                integrator.setPrompt("Scan");
                integrator.setCameraId(0);
                integrator.setBeepEnabled(false);
                integrator.setBarcodeImageEnabled(true);
                integrator.initiateScan();
            }
        });

        return view;
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if (result.getContents() != null) {
            if (result.getContents() != null){
                String scanContent = result.getContents();
                String scanFormat = result.getFormatName();

                // display it on screen
                formatTxt.setText("FORMAT: " + scanFormat);
                contentTxt.setText("CONTENT: " + scanContent);
            } else {
                Toast toast = Toast.makeText(getContext(),"No scan data received!", Toast.LENGTH_SHORT);
                toast.show();
            }
        }
    }
}

my xml

<RelativeLayout 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" >
    <Button android:id="@+id/scan_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:text="@string/scan" />

    <TextView
        android:id="@+id/scanFormat"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textIsSelectable="true"
        android:layout_centerHorizontal="true"
        android:layout_below="@id/scan_button" />
    <TextView
        android:id="@+id/scanContent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textIsSelectable="true"
        android:layout_centerHorizontal="true"
        android:layout_below="@id/scanFormat" />
</RelativeLayout>

i have edit the code to this

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle   savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_one, container, false);
    scan_btn = (Button) view.findViewById(R.id.scan_button);
    formatTxt = (TextView) view.findViewById(R.id.scanFormat);
    contentTxt = (TextView) view.findViewById(R.id.scanContent);
    final Activity activity = getActivity();
    scan_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            IntentIntegrator integrator = new IntentIntegrator(activity);
            integrator.setDesiredBarcodeFormats(IntentIntegrator.PRODUCT_CODE_TYPES);
            integrator.setPrompt("Scan");
            integrator.setCameraId(0);
            integrator.setBeepEnabled(false);
            integrator.setBarcodeImageEnabled(true);
            integrator.initiateScan();
        }
    });
    return view;
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
    if (result.getContents() != null) {
        if (result.getContents() == null){
            Toast toast = Toast.makeText(getContext(),"No scan data received!", Toast.LENGTH_SHORT);
            toast.show();


    }else{

            String scanContent = result.getContents();
            String scanFormat = result.getFormatName();

            // display it on screen
            formatTxt.setText("FORMAT: " + scanFormat);
            contentTxt.setText("CONTENT: " + scanContent);
    }
}
}}

still cant display the format and contents

Answer 1

Initialize your formatTxt & contentTxt in your onCreateView() method ! Scan is alright, it just gives NPE because of not initializing TextView

scan_btn = (Button) view.findViewById(R.id.scan_button);
formatTxt = (TextView) view.findViewById(R.id.scanFormat);
contentTxt = (TextView) view.findViewById(R.id.scanContent);

and in your activityResult

@Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if (result.getContents() != null) {
            String scanContent = result.getContents();
            String scanFormat = result.getFormatName();

            // display it on screen
            formatTxt.setText("FORMAT: " + scanFormat);
            contentTxt.setText("CONTENT: " + scanContent);
        }
    }

update: that's how it look in your code.

public class ThreeFragment extends Fragment{

    public ThreeFragment() {
        // Required empty public constructor
    }

    Button scan_btn;
    EditText Edit_current;
    TextView formatTxt, contentTxt;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle   savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_one, container, false);
    scan_btn = (Button) view.findViewById(R.id.scan_button);
    //initialize the textViews 
    formatTxt = (TextView) view.findViewById(R.id.scanFormat);
    contentTxt = (TextView) view.findViewById(R.id.scanContent);
        final Activity activity = getActivity();
        scan_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                IntentIntegrator integrator = new IntentIntegrator(activity);
                integrator.setDesiredBarcodeFormats(IntentIntegrator.PRODUCT_CODE_TYPES);
                integrator.setPrompt("Scan");
                integrator.setCameraId(0);
                integrator.setBeepEnabled(false);
                integrator.setBarcodeImageEnabled(true);
                integrator.initiateScan();
            }
        });

        return view;
    }

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
                IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
                if (result.getContents() != null) {
                    String scanContent = result.getContents();
                    String scanFormat = result.getFormatName();

                    // display it on screen
                    formatTxt.setText("FORMAT: " + scanFormat);
                    contentTxt.setText("CONTENT: " + scanContent);
                }else {
                    Toast toast = Toast.makeText(getContext(),"No scan data received!", Toast.LENGTH_SHORT);
                    toast.show();
                }
            }

    }

Answer 2

    package com.sp.ez_mart_xy;

import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;

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


        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new OneFragment(), "NAVIGATION");
        adapter.addFragment(new TwoFragment(), "HOME");
        adapter.addFragment(new ThreeFragment(), "PRICE-CHECKER");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
}

this is my mainactivty but i dont see any errors

Answer 3

There are at least two issues with your code:

1. You have the same if statement twice:

    if (result.getContents() != null) { if (result.getContents() != null){ 

   The outer one does not have an else , so you will not know when the condition fails even though the inner one does have an else .

2. formatTxt is not initialized. You need to add a call to findViewById() somewhere in onCreateView() to initialize it.