Fragment in java error : <p>Help me to resolve this bug. This is the logcat and fragment java code. I want to make tab layout. In the tab layout, i want to fill a different java logic. But, i dont know must place the code. Please help me</p>

<pre><code>04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime: FATAL EXCEPTION: main
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime: Process: com.prakosoft.physhics.calculator, PID: 27113
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at info.androidhive.materialtabs.fragments.OneFragment.onCreateView(OneFragment.java:39)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.view.ViewPager.populate(ViewPager.java:1177)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1545)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:664)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:731)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5536)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2618)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.View.measure(View.java:17637)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2019)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1177)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1383)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1065)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5901)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.Choreographer.doCallbacks(Choreographer.java:580)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.Choreographer.doFrame(Choreographer.java:550)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.os.Handler.handleCallback(Handler.java:739)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:95)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:211)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5389)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:372)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
    04-03 12:17:10.478 27113-27113/com.prakosoft.physhics.calculator E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
</code></pre>

<p>This is fragment java code</p>

<pre><code>public OneFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_one, container, false);

        b = (EditText) getView().findViewById(R.id.b);
        i = (EditText) getView().findViewById(R.id.i);
        l = (EditText) getView().findViewById(R.id.l);
        hasil = (TextView) getView().findViewById(R.id.hasil);
        hitung = (Button) getView().findViewById(R.id.hitung);
        spinner = (Spinner) getView().findViewById(R.id.spinner);

        List&lt;String&gt; list = new ArrayList&lt;String&gt;();
        list.add("");
        list.add("0");
        list.add("1/2");
        list.add("1/2√2");
        list.add("1/2√3");
        list.add("1");

        hitung.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String be = b.getText().toString().trim();
                String ii = i.getText().toString().trim();
                String el = l.getText().toString().trim();
                String text = spinner.getSelectedItem().toString();

                if (spinner.getSelectedItem().toString().equals("1")) {
                    if (b.getText().toString().equals("") || i.getText().toString().equals("") || l.getText().toString().equals("")) {
                        Toast.makeText(getActivity().getApplicationContext(), "Isi terlebih dahulu", Toast.LENGTH_SHORT).show();
                    } else {
                        Integer bee = Integer.parseInt(be);
                        Integer iii = Integer.parseInt(ii);
                        Integer eel = Integer.parseInt(el);
                        Integer tekss = Integer.parseInt(text);
                        Integer gaya = (bee * iii * eel) * tekss;

                        hasil.setText("Gaya Lorentz = " + gaya);
                    }
                } else if (spinner.getSelectedItem().toString().equals("1/2")) {
                    if (b.getText().toString().equals("") || i.getText().toString().equals("") || l.getText().toString().equals("")) {
                        Toast.makeText(getActivity().getApplicationContext(), "Isi terlebih dahulu", Toast.LENGTH_SHORT).show();
                    } else {
                        Integer bee = Integer.parseInt(be);
                        Integer iii = Integer.parseInt(ii);
                        Integer eel = Integer.parseInt(el);
                        Integer gaya = (bee * iii * eel) / 2;

                        hasil.setText("Gaya Lorentz = " + gaya);
                    }
                } else if (spinner.getSelectedItem().toString().equals("1/2√2")) {
                    if (b.getText().toString().equals("") || i.getText().toString().equals("") || l.getText().toString().equals("")) {
                        Toast.makeText(getActivity().getApplicationContext(), "Isi terlebih dahulu", Toast.LENGTH_SHORT).show();
                    } else {
                        Integer bee = Integer.parseInt(be);
                        Integer iii = Integer.parseInt(ii);
                        Integer eel = Integer.parseInt(el);
                        double akar = Math.sqrt(2);
                        Integer gaya = (bee * iii * eel) / 2;
                        double hasilakar = gaya * akar;

                        hasil.setText("Gaya Lorentz = " + hasilakar);
                    }
                } else if (spinner.getSelectedItem().toString().equals("1/2√3")) {
                    if (b.getText().toString().equals("") || i.getText().toString().equals("") || l.getText().toString().equals("")) {
                        Toast.makeText(getActivity().getApplicationContext(), "Isi terlebih dahulu", Toast.LENGTH_SHORT).show();
                    } else {
                        Integer bee = Integer.parseInt(be);
                        Integer iii = Integer.parseInt(ii);
                        Integer eel = Integer.parseInt(el);
                        double akar = Math.sqrt(3);
                        Integer gaya = (bee * iii * eel) / 2;
                        double hasilakar = gaya * akar;

                        hasil.setText("Gaya Lorentz = " + hasilakar);
                    }
                } else if (spinner.getSelectedItem().toString().equals("0")) {
                    if (b.getText().toString().equals("") || i.getText().toString().equals("") || l.getText().toString().equals("")) {
                        Toast.makeText(getActivity().getApplicationContext(), "Isi terlebih dahulu", Toast.LENGTH_SHORT).show();
                    } else {
                        hasil.setText("Gaya Lorentz = 0");
                    }
                } else if (spinner.getSelectedItem().toString().equals("")) {
                    Toast.makeText(getActivity().getApplicationContext(), "Pilih sin θ", Toast.LENGTH_SHORT).show();
                }

            }
        });

        ArrayAdapter&lt;String&gt; dataAdapter = new ArrayAdapter&lt;String&gt;(getActivity(), android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(dataAdapter);

        return view;
    }
</code></pre>
