Activity

package ca.roumani.taxcalc;

import android.graphics.Typeface;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.TextView;

public class TaxActivity extends AppCompatActivity
{

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tax);
    }
    public void buttonClicked(View v)
    {

            View incomeView = findViewById(R.id.incomebox);
            EditText incomeEdit = (EditText) incomeView;
            String incomeString = incomeEdit.getText().toString();
            TaxModel model = new TaxModel(incomeString);

            View outputBox = findViewById(R.id.output);
            ViewGroup output = (ViewGroup) outputBox;

            output.removeAllViews();


            TextView taxLabel = new TextView(this);
            taxLabel.setText("Income Tax:");
            output.addView(taxLabel);

            TextView taxAnswer = new TextView(this);
            taxAnswer.setTypeface(null, Typeface.BOLD);
            String answer1 = model.getTax();
            taxAnswer.setText(answer1);
            output.addView(taxAnswer);


            TextView avgLabel = new TextView(this);
            avgLabel.setText("Average Rate:");
            output.addView(avgLabel);

            TextView averageAnswer = new TextView(this);
            averageAnswer.setTypeface(null, Typeface.BOLD);
            String answer2 = model.getAverageRate();
            averageAnswer.setText(answer2);
            output.addView(averageAnswer);

            TextView mrgLabel = new TextView(this);
            mrgLabel.setText("Marginal Rate:");
            output.addView(mrgLabel);

            TextView mrgAnswer = new TextView(this);
            mrgAnswer.setTypeface(null, Typeface.BOLD);
            String answer3 = model.getMarginalRate();
            mrgAnswer.setText(answer3);
            output.addView(mrgAnswer);


            TextView cppLabel = new TextView(this);
            cppLabel.setText("CPP:");
            output.addView(cppLabel);

            TextView cppAnswer = new TextView(this);
            cppAnswer.setTypeface(null, Typeface.BOLD);
            String answer4 = model.getCPP();
            cppAnswer.setText(answer4);
            output.addView(cppAnswer);


            TextView eiLabel = new TextView(this);
            eiLabel.setText("EI:");
            output.addView(eiLabel);

            TextView eiAnswer = new TextView(this);
            eiAnswer.setTypeface(null, Typeface.BOLD);
            String answer5 = model.getEI();
            eiAnswer.setText(answer5);
            output.addView(eiAnswer);
        }



    }




Model

package ca.roumani.taxcalc;


public class TaxModel
{
    private double income;
    private double tax, average, marginal, cpp, ei;

    public static final double BRACKET_0 = 11475.0;
    public static final double BRACKET_1 = 33808.0;
    public static final double BRACKET_2 = 40895.0;
    public static final double BRACKET_3 = 63823.0;
    public static final double RATE_1 = 22.79 / 100.0;
    public static final double RATE_2 = 33.23 / 100.0;
    public static final double RATE_3 = 45.93 / 100.0;
    public static final double RATE_4 = 52.75 / 100.0;

    public static final double EI_RATE = 1.63/100.0;
    public static final double EI_MAX = 836.19;

    public static final double CPP_RATE = 4.95/100.0;
    public static final double CPP_MAX = 2564.10;
    public static final double CPP_EXEMPT = 3500.0;

    public TaxModel(String p)
    {
        this.income = Double.parseDouble(p);
    }

    public void setIncome(double i)
    {
        this.income = i;
    }

    public String getTax()
    {
        if (income <= BRACKET_0)
        {
            tax = 0;
            String tax_2 = String.format("%,.2f",tax);
            return tax_2;
        } else if (income > BRACKET_0 && income <= 45283)
        {
            tax = ((income - BRACKET_0) * 0.2279);
            String tax_2 = String.format("%,.2f",tax);
            return tax_2;
        } else if (income > 45283 && income <= 86178)
        {
            tax = (((income - BRACKET_0) - BRACKET_1) * RATE_2) + (BRACKET_1 * RATE_1);
            String tax_2 = String.format("%,.2f",tax);
            return tax_2;
        } else if ((income > 86178 && income <= 150003))
        {
            tax = (((income - BRACKET_0) - BRACKET_2) * RATE_3) +  (BRACKET_2 * RATE_1);
            String tax_2 = String.format("%,.2f",tax);
            return tax_2;
        } else
        {
            tax = (((income - BRACKET_0) - BRACKET_3) * RATE_4)  + (BRACKET_3 * RATE_1);
            String tax_2 = String.format("%,.2f",tax);
            return tax_2;
        }
    }

    public String getAverageRate()
    {
        average = (tax / income) * 100;
        if(income == 0)
        {
            average = 0;
        }
        String average2 = String.format("%.0f", average);
        return average2 + "%";

    }

    public String getMarginalRate()
    {
        if (income <= BRACKET_0)
        {
            marginal = 0;
            String marginal_2 = String.format("%.0f", marginal);
            return marginal_2 + "%";
        } else if (income > BRACKET_0 && income <= 45283)
        {
            marginal = 22.79;
            String marginal_2 = String.format("%.0f", marginal);
            return marginal_2 + "%";
        } else if (income > 45283 && income <= 86178)
        {
            marginal = 33.23;
            String marginal_2 = String.format("%.0f", marginal);
            return marginal_2 + "%";
        } else if ((income > 86178 && income <= 150003))
        {
            marginal = 45.93;
            String marginal_2 = String.format("%.0f", marginal);
            return marginal_2 + "%";
        } else {
            marginal = 52.75;
            String marginal_2 = String.format("%.0f", marginal);
            return marginal_2 + "%";
        }
    }

    public String getCPP()
    {
        cpp = (income - CPP_EXEMPT) * CPP_RATE;
        if(cpp >= CPP_MAX)
        {
            cpp = CPP_MAX;
            String cpp2 = String.format("%,.0f", cpp);
            return cpp2;
        } else {
            String cpp2 = String.format("%,.0f", cpp);
            return cpp2;        }
    }

    public String getEI()
    {
        ei = income * EI_RATE;
        if(ei > EI_MAX)
        {
            ei = EI_MAX;
            String ei_2 = String.format("%,.0f", ei);
            return ei_2;
        } else {
            String ei_2 = String.format("%,.0f", ei);
            return ei_2;        }
    }
}


XML

<?xml version="1.0" encoding="utf-8"?>
<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="ca.roumani.taxcalc.TaxActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Annual Income"
        android:id="@+id/textView"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"/>

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="numberDecimal"
        android:ems="10"
        android:id="@+id/incomebox"
        android:layout_below="@+id/textView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Compute Tax"
        android:id="@+id/button"
        android:layout_below="@+id/incomebox"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:onClick="buttonClicked"/>

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/button"
        android:id="@+id/output">
    </LinearLayout>
</RelativeLayout>