private void initFieldDisplayMapAndFieldLengthMap(@Nullable List<Field> initialFields) {
    fieldDisplayMap.clear();
    fieldLengthMap.clear();
    for (FieldInfo fieldInfo : topScreenModel.getFieldInfos()) {
      if (initialFields != null) {
        fieldDisplayMap.put(fieldInfo.getField(), initialFields.contains(fieldInfo.getField()));
      } else {
        fieldDisplayMap.put(fieldInfo.getField(), fieldInfo.isDisplayByDefault());
      }
      fieldLengthMap.put(fieldInfo.getField(), fieldInfo.getDefaultLength());
    }
  }
The presentation logic for the top screen.
hbase-hbtop/src/main/java/org/apache/hadoop/hbase/hbtop/screen/top/TopScreenPresenter.java