The problem with the library MPAndroidChart v3.1.0

There is a class ScoreCardActivity where the work with the MPAndroidChart library is described, namely the work with PieChart (round diagram). The studio highlights in red such lines:

public class ScoreCardActivity extends BaseActivity implements OnChartValueSelectedListener

(getString (R.string.score_card))

(yvalues, AppConstants.EMPTY_STRING)

(xVals, dataSet)

The question is, why is this happening?

public class ScoreCardActivity extends BaseActivity implements OnChartValueSelectedListener { private Activity mActivity; private Context mContext; private Button mBtnShare, mBtnPlayAgain; private TextView mScoreTextView, mWrongAnsTextView, mSkipTextView, mGreetingTextView; private int mScore, mWrongAns, mSkip; private int mQuestionsCount; private String mCategoryId; private ArrayList<ResultModel> mResultList; private ResultAdapter mAdapter = null; private RecyclerView mRecyclerResult; private PieChart mPieChart; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); initVar(); initView(); initFunctionality(); initListener(); } private void initVar() { mActivity = ScoreCardActivity.this; mContext = mActivity.getApplicationContext(); Intent intent = getIntent(); if (intent != null) { mScore = intent.getIntExtra(AppConstants.BUNDLE_KEY_SCORE, 0); mWrongAns = intent.getIntExtra(AppConstants.BUNDLE_KEY_WRONG_ANS, 0); mQuestionsCount = intent.getIntExtra(AppConstants.QUESTIONS_IN_TEST, 0); mCategoryId = intent.getStringExtra(AppConstants.BUNDLE_KEY_INDEX); mResultList = intent.getParcelableArrayListExtra(AppConstants.BUNDLE_KEY_ITEM); } } private void initView() { setContentView(R.layout.activity_score_card); mRecyclerResult = (RecyclerView) findViewById(R.id.rvContentScore); mRecyclerResult.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)); mBtnShare = (Button) findViewById(R.id.btn_share); mBtnPlayAgain = (Button) findViewById(R.id.btn_play_again); mScoreTextView = (TextView) findViewById(R.id.txt_score); mWrongAnsTextView = (TextView) findViewById(R.id.txt_wrong); mSkipTextView = (TextView) findViewById(R.id.txt_skip); mGreetingTextView = (TextView) findViewById(R.id.greeting_text); initToolbar(true); setToolbarTitle(getResources().getString(R.string.score_card)); enableUpButton(); } public void initFunctionality() { mSkip = mQuestionsCount - (mScore + mWrongAns); mScoreTextView.setText(String.valueOf(mScore)); mWrongAnsTextView.setText(String.valueOf(mWrongAns)); mSkipTextView.setText(String.valueOf(mSkip)); float actualScore = ((float) mScore / (float) (mScore + mWrongAns + mSkip)) * AppConstants.MULTIPLIER_GRADE; switch (Math.round(actualScore)) { case 10: case 9: case 8: mGreetingTextView.setText(Html.fromHtml(getResources().getString(R.string.greeting_text3))); break; case 7: case 6: case 5: mGreetingTextView.setText(Html.fromHtml(getResources().getString(R.string.greeting_text2))); break; default: mGreetingTextView.setText(Html.fromHtml(getResources().getString(R.string.greeting_text1))); break; } showPieChart(); mAdapter = new ResultAdapter(mContext, mActivity, mResultList); mRecyclerResult.setAdapter(mAdapter); // show full-screen ads // TODO AdsUtilities.getInstance(mContext).showFullScreenAd(); // show banner ads // TODO AdsUtilities.getInstance(mContext).showBannerAd((AdView) findViewById(R.id.adsView)); } public void initListener() { mBtnShare.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Intent sendIntent = new Intent(); sendIntent.setAction(Intent.ACTION_SEND); sendIntent.putExtra(Intent.EXTRA_TEXT, getString(R.string.sharing_text, mScore) + " https://play.google.com/store/apps/details?id=" + mActivity.getPackageName()); sendIntent.setType("text/plain"); startActivity(Intent.createChooser(sendIntent, getResources().getText(R.string.send_to))); } }); mBtnPlayAgain.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { ActivityUtilities.getInstance().invokeCommonQuizActivity(mActivity, QuizPromptActivity.class, mCategoryId, true); } }); } public void showPieChart() { mPieChart = (PieChart) findViewById(R.id.piechart); mPieChart.setUsePercentValues(true); mPieChart.setDrawHoleEnabled(true); mPieChart.setTransparentCircleRadius(AppConstants.TRANSPARENT_CIRCLE_RADIUS); mPieChart.setHoleRadius(AppConstants.TRANSPARENT_CIRCLE_RADIUS); mPieChart.setDescription(getString(R.string.score_card)); mPieChart.animateXY(AppConstants.ANIMATION_VALUE, AppConstants.ANIMATION_VALUE); ArrayList<Entry> yvalues = new ArrayList<Entry>(); yvalues.add(new Entry(mScore, AppConstants.BUNDLE_KEY_ZERO_INDEX)); yvalues.add(new Entry(mWrongAns, AppConstants.BUNDLE_KEY_SECOND_INDEX)); yvalues.add(new Entry(mSkip, AppConstants.BUNDLE_KEY_FIRST_INDEX)); PieDataSet dataSet = new PieDataSet(yvalues, AppConstants.EMPTY_STRING); dataSet.setColors(ColorTemplate.JOYFUL_COLORS); ArrayList<String> xVals = new ArrayList<String>(); xVals.add(getString(R.string.score)); xVals.add(getString(R.string.wrong)); xVals.add(getString(R.string.skipped)); PieData data = new PieData(xVals, dataSet); // In percentage Term data.setValueFormatter(new PercentFormatter()); mPieChart.setData(data); } @Override public void onValueSelected(Entry e, int dataSetIndex, Highlight h) { if (e == null) return; } @Override public void onNothingSelected() { } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: ActivityUtilities.getInstance().invokeNewActivity(mActivity, MainActivity.class, true); return true; } return super.onOptionsItemSelected(item); } @Override public void onBackPressed() { ActivityUtilities.getInstance().invokeNewActivity(mActivity, MainActivity.class, true); }}