Android Studio : Error parsing XML, failed to build application
<p>When i'm trying to build my application it gives me the following to errors.</p>

<p>Error:(21) Error parsing XML: not well-formed (invalid token)
Error:Execution failed for task ':app:processDebugResources'.</p>

<blockquote>
  <p>com.android.ide.common.process.ProcessException: Failed to execute aapt</p>
</blockquote>

<p>Here is my XML code, and this is the only XML code, please help me.</p>

<pre><code>package com.example.madhur.calculator;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class InnerWorkings extends Activity implements View.OnClickListener {

    TextView tvvresults;
    Button bvBackSpace, bvClear, bvPlusMinus, bvRoot, bvDivision, bvMultiply, bvSubtract, bvDot, bvEqual, bvAddition;
    Button bv0, bv1, bv2, bv3, bv4, bv5, bv6, bv7, bv8, bv9;
    int iResults, container, arithmaticCode, finalCalculation, remainder;

    protected void onCreate(Bundle calculations) {
        super.onCreate(calculations);

        Initialization();
    }

    private void Initialization() {

        tvvresults = (TextView) findViewById(R.id.tvResults);

        bvBackSpace = (Button) findViewById(R.id.bBackSpace);
        bvClear = (Button) findViewById(R.id.bClear);
        bvPlusMinus = (Button) findViewById(R.id.bPlusMinus);
        bvRoot = (Button) findViewById(R.id.bRoot);
        bvDivision = (Button) findViewById(R.id.bDivision);
        bvMultiply = (Button) findViewById(R.id.bMultiply);
        bvSubtract = (Button) findViewById(R.id.bSubtract);
        bvDot = (Button) findViewById(R.id.bDot);
        bvEqual = (Button) findViewById(R.id.bEqual);
        bvAddition = (Button) findViewById(R.id.bAddition);
        bv0 = (Button) findViewById(R.id.b0);
        bv1 = (Button) findViewById(R.id.b1);
        bv2 = (Button) findViewById(R.id.b2);
        bv3 = (Button) findViewById(R.id.b3);
        bv4 = (Button) findViewById(R.id.b4);
        bv5 = (Button) findViewById(R.id.b5);
        bv6 = (Button) findViewById(R.id.b6);
        bv7 = (Button) findViewById(R.id.b7);
        bv8 = (Button) findViewById(R.id.b8);
        bv9 = (Button) findViewById(R.id.b9);

        bvBackSpace.setOnClickListener(this);
        bvClear.setOnClickListener(this);
        bvPlusMinus.setOnClickListener(this);
        bvRoot.setOnClickListener(this);
        bvDivision.setOnClickListener(this);
        bvMultiply.setOnClickListener(this);
        bvSubtract.setOnClickListener(this);
        bvDot.setOnClickListener(this);
        bvEqual.setOnClickListener(this);
        bvAddition.setOnClickListener(this);
        bv0.setOnClickListener(this);
        bv1.setOnClickListener(this);
        bv2.setOnClickListener(this);
        bv3.setOnClickListener(this);
        bv4.setOnClickListener(this);
        bv5.setOnClickListener(this);
        bv6.setOnClickListener(this);
        bv7.setOnClickListener(this);
        bv8.setOnClickListener(this);
        bv9.setOnClickListener(this);
    }

    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.bBackSpace:
                remainder = iResults % 10;
                iResults = iResults - remainder;
                tvvresults.setText(iResults);
                break;
            case R.id.bClear:
                iResults = 0;
                tvvresults.setText(iResults);
                break;
            case R.id.bPlusMinus:
                iResults = iResults * (-1);
                tvvresults.setText(iResults);
                break;
            case R.id.bRoot:

                break;
            case R.id.bDivision:
                arithmaticCode = 1;
                container = iResults;
                iResults = 0;
                break;
            case R.id.bMultiply:
                arithmaticCode = 2;
                container = iResults;
                iResults = 0;
                break;
            case R.id.bSubtract:
                arithmaticCode = 3;
                container = iResults;
                iResults = 0;
                break;
            case R.id.bDot:

                break;
            case R.id.bEqual:
                Calculations();
                break;
            case R.id.bAddition:
                arithmaticCode = 4;
                container = iResults;
                iResults = 0;
                break;
            case R.id.b0:
                iResults = (iResults * 10);
                tvvresults.setText(iResults);
                break;
            case R.id.b1:
                iResults = (iResults * 10) + 1;
                tvvresults.setText(iResults);
                break;
            case R.id.b2:
                iResults = (iResults * 10) + 2;
                tvvresults.setText(iResults);
                break;
            case R.id.b3:
                iResults = (iResults * 10) + 3;
                tvvresults.setText(iResults);
                break;
            case R.id.b4:
                iResults = (iResults * 10) + 4;
                tvvresults.setText(iResults);
                break;
            case R.id.b5:
                iResults = (iResults * 10) + 5;
                tvvresults.setText(iResults);
                break;
            case R.id.b6:
                iResults = (iResults * 10) + 6;
                tvvresults.setText(iResults);
                break;
            case R.id.b7:
                iResults = (iResults * 10) + 7;
                tvvresults.setText(iResults);
                break;
            case R.id.b8:
                iResults = (iResults * 10) + 8;
                tvvresults.setText(iResults);
                break;
            case R.id.b9:
                iResults = (iResults * 10) + 9;
                tvvresults.setText(iResults);
                break;
        }
    }

    private void Calculations() {
        if (arithmaticCode == 1) {
            finalCalculation = container / iResults;
            tvvresults.setText(finalCalculation);
        }
        if (arithmaticCode == 2) {
            finalCalculation = container * iResults;
            tvvresults.setText(finalCalculation);
        }
        if (arithmaticCode == 3){
            finalCalculation = container - iResults;
            tvvresults.setText(finalCalculation);
        }
        if (arithmaticCode == 4){
            finalCalculation = container + iResults;
            tvvresults.setText(finalCalculation);
        }
    }
}
</code></pre>

<pre class="lang-html prettyprint-override"><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dp"&gt;

    &lt;RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"&gt;

        &lt;TextView
            android:gravity="center"
            android:textSize="20dp"
            android:text="0"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            android:id="@+id/tvResults" /&gt;

        &lt;Button
            android:text="&lt;---"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bBackSpace"
            android:layout_marginTop="21dp"
            android:layout_below="@id/tvResults"
            android:layout_alignParentStart="true"
            android:layout_marginStart="21dp"/&gt;

        &lt;Button
            android:text="C"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bClear"
            android:layout_below="@id/tvResults"
            android:layout_toEndOf="@id/bBackSpace"
            android:layout_marginStart="20dp"
            android:layout_marginTop="21dp"/&gt;

        &lt;Button
            android:text="+/-"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bPlusMinus"
            android:layout_below="@id/tvResults"
            android:layout_toStartOf="@id/bRoot"
            android:layout_marginEnd="20dp"
            android:layout_marginTop="21dp" /&gt;

        &lt;Button
            android:text="-v"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bRoot"
            android:layout_marginEnd="21dp"
            android:layout_marginTop="21dp"
            android:layout_below="@id/tvResults"
            android:layout_alignParentEnd="true" /&gt;

        &lt;Button
            android:text="7"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b7"
            android:layout_below="@id/bBackSpace"
            android:layout_alignParentStart="true"
            android:layout_marginStart="21dp"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="8"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b8"
            android:layout_below="@id/bBackSpace"
            android:layout_toEndOf="@id/bBackSpace"
            android:layout_marginStart="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="9"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b9"
            android:layout_below="@id/bBackSpace"
            android:layout_toStartOf="@id/bDivision"
            android:layout_marginEnd="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="/"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bDivision"
            android:layout_marginEnd="21dp"
            android:layout_below="@id/bBackSpace"
            android:layout_alignParentEnd="true"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="4"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b4"
            android:layout_below="@id/b7"
            android:layout_alignParentStart="true"
            android:layout_marginStart="21dp"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="5"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b5"
            android:layout_below="@id/b8"
            android:layout_toEndOf="@id/b4"
            android:layout_marginStart="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="6"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b6"
            android:layout_below="@id/b9"
            android:layout_toStartOf="@id/bMultiply"
            android:layout_marginEnd="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="*"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bMultiply"
            android:layout_marginEnd="21dp"
            android:layout_below="@id/bDivision"
            android:layout_alignParentEnd="true"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="1"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b1"
            android:layout_below="@id/b4"
            android:layout_alignParentStart="true"
            android:layout_marginStart="21dp"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="2"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b2"
            android:layout_below="@id/b5"
            android:layout_toEndOf="@id/b4"
            android:layout_marginStart="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="3"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b3"
            android:layout_below="@id/b6"
            android:layout_toStartOf="@id/bSubtract"
            android:layout_marginEnd="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="-"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bSubtract"
            android:layout_marginEnd="21dp"
            android:layout_below="@id/bMultiply"
            android:layout_alignParentEnd="true"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="0"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/b0"
            android:layout_below="@id/b1"
            android:layout_alignParentStart="true"
            android:layout_marginStart="21dp"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="="
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bEqual"
            android:layout_below="@id/b3"
            android:layout_toStartOf="@id/bAddition"
            android:layout_marginEnd="20dp"
            android:layout_marginTop="20dp" /&gt;

        &lt;Button
            android:text="+"
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bAddition"
            android:layout_marginEnd="21dp"
            android:layout_below="@id/bSubtract"
            android:layout_alignParentEnd="true"
            android:layout_marginTop="20dp"/&gt;

        &lt;Button
            android:text="."
            android:textStyle="bold"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:id="@+id/bDot"
            android:layout_below="@id/b2"
            android:layout_toEndOf="@id/b1"
            android:layout_marginStart="20dp"
            android:layout_marginTop="20dp"/&gt;

    &lt;/RelativeLayout&gt;
&lt;/LinearLayout&gt;
</code></pre>