Need help with bug in personal project

package com.example.straml1.tfsacalculator.ui;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.EditText;

import com.example.straml1.tfsacalculator.R;
import com.example.straml1.tfsacalculator.model.Calculator;

public class TFSAActivity extends AppCompatActivity {

    public static final String TAG = TFSAActivity.class.getSimpleName();
    private EditText tfsaValue;

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

        tfsaValue = findViewById(R.id.tfsaValue);

        Intent intent = getIntent();
        String year = intent.getStringExtra(getString(R.string.key_year));
        if (year == null || year.isEmpty()) {
            year = "Before 1992";
        }
        Log.d(TAG, year);
        showResult(year);
    }

    private void showResult(String year) {
        Calculator calculator = new Calculator();
        int answer = calculator.limitByAge(year);
        tfsaValue.setText(String.valueOf(answer));

    }
}

package com.example.straml1.tfsacalculator.model;


import java.util.Arrays;

public class Calculator {

    // TFSA contributions up to 2018
    private int[] yearlyLimit = {5000, 5000, 5000, 5000, 5500, 5500, 10000, 5500, 5500, 5500};

    public int limitByAge(String year) {
        int roomTotal = 0;
        if (year == "Before 1992") {
            for (int num : yearlyLimit) {
                roomTotal += num;
            }
        }
        else {
            int yearBorn = Integer.parseInt(year);
            int yearsToSubtract = 18 - (2009 - yearBorn);
            int[] validContributions = Arrays.copyOfRange(yearlyLimit, 0+yearsToSubtract, yearlyLimit.length);
            for (int num : validContributions) {
                roomTotal += num;
            }
        }
        return roomTotal;
    }
}