Notes

package zone.eloy.projects.androidcalculator;


import android.graphics.Color;
import android.graphics.PorterDuff;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import java.math.BigDecimal;

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

public class MainActivity extends AppCompatActivity implements View.OnClickListener, View.OnTouchListener
{
private int openParenthesis = 0;

private boolean dotUsed = false;

private boolean equalClicked = false;
private String lastExpression = "";

private final static int EXCEPTION = -1;
private final static int IS_NUMBER = 0;
private final static int IS_OPERAND = 1;
private final static int IS_OPEN_PARENTHESIS = 2;
private final static int IS_CLOSE_PARENTHESIS = 3;
private final static int IS_DOT = 4;

Button buttonNumber0;
Button buttonNumber1;
Button buttonNumber2;
Button buttonNumber3;
Button buttonNumber4;
Button buttonNumber5;
Button buttonNumber6;
Button buttonNumber7;
Button buttonNumber8;
Button buttonNumber9;

Button buttonClear;
Button buttonParentheses;
Button buttonPercent;
Button buttonDivision;
Button buttonMultiplication;
Button buttonSubtraction;
Button buttonAddition;
Button buttonEqual;
Button buttonDot;

TextView textViewInputNumbers;

ScriptEngine scriptEngine;

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
scriptEngine = new ScriptEngineManager().getEngineByName("rhino");

initializeViewVariables();
setOnClickListeners();
setOnTouchListener();
}

private void initializeViewVariables()
{
buttonNumber0 = (Button) findViewById(R.id.button_zero);
buttonNumber1 = (Button) findViewById(R.id.button_one);
buttonNumber2 = (Button) findViewById(R.id.button_two);
buttonNumber3 = (Button) findViewById(R.id.button_three);
buttonNumber4 = (Button) findViewById(R.id.button_four);
buttonNumber5 = (Button) findViewById(R.id.button_five);
buttonNumber6 = (Button) findViewById(R.id.button_six);
buttonNumber7 = (Button) findViewById(R.id.button_seven);
buttonNumber8 = (Button) findViewById(R.id.button_eight);
buttonNumber9 = (Button) findViewById(R.id.button_nine);

buttonClear = (Button) findViewById(R.id.button_clear);
buttonParentheses = (Button) findViewById(R.id.button_parentheses);
buttonPercent = (Button) findViewById(R.id.button_percent);
buttonDivision = (Button) findViewById(R.id.button_division);
buttonMultiplication = (Button) findViewById(R.id.button_multiplication);
buttonSubtraction = (Button) findViewById(R.id.button_subtraction);
buttonAddition = (Button) findViewById(R.id.button_addition);
buttonEqual = (Button) findViewById(R.id.button_equal);
buttonDot = (Button) findViewById(R.id.button_dot);
textViewInputNumbers = (TextView) findViewById(R.id.textView_input_numbers);
}

private void setOnClickListeners()
{
buttonNumber0.setOnClickListener(this);
buttonNumber1.setOnClickListener(this);
buttonNumber2.setOnClickListener(this);
buttonNumber3.setOnClickListener(this);
buttonNumber4.setOnClickListener(this);
buttonNumber5.setOnClickListener(this);
buttonNumber6.setOnClickListener(this);
buttonNumber7.setOnClickListener(this);
buttonNumber8.setOnClickListener(this);
buttonNumber9.setOnClickListener(this);

buttonClear.setOnClickListener(this);
buttonParentheses.setOnClickListener(this);
buttonPercent.setOnClickListener(this);
buttonDivision.setOnClickListener(this);
buttonMultiplication.setOnClickListener(this);
buttonSubtraction.setOnClickListener(this);
buttonAddition.setOnClickListener(this);
buttonEqual.setOnClickListener(this);
buttonDot.setOnClickListener(this);
}

private void setOnTouchListener()
{
buttonNumber0.setOnTouchListener(this);
buttonNumber1.setOnTouchListener(this);
buttonNumber2.setOnTouchListener(this);
buttonNumber3.setOnTouchListener(this);
buttonNumber4.setOnTouchListener(this);
buttonNumber5.setOnTouchListener(this);
buttonNumber6.setOnTouchListener(this);
buttonNumber7.setOnTouchListener(this);
buttonNumber8.setOnTouchListener(this);
buttonNumber9.setOnTouchListener(this);

buttonClear.setOnTouchListener(this);
buttonParentheses.setOnTouchListener(this);
buttonPercent.setOnTouchListener(this);
buttonDivision.setOnTouchListener(this);
buttonMultiplication.setOnTouchListener(this);
buttonSubtraction.setOnTouchListener(this);
buttonAddition.setOnTouchListener(this);
buttonDot.setOnTouchListener(this);
}

@Override
public void onClick(View view)
{
switch (view.getId())
{
case R.id.button_zero:
if (addNumber("0")) equalClicked = false;
break;
case R.id.button_one:
if (addNumber("1")) equalClicked = false;
break;
case R.id.button_two:
if (addNumber("2")) equalClicked = false;
break;
case R.id.button_three:
if (addNumber("3")) equalClicked = false;
break;
case R.id.button_four:
if (addNumber("4")) equalClicked = false;
break;
case R.id.button_five:
if (addNumber("5")) equalClicked = false;
break;
case R.id.button_six:
if (addNumber("6")) equalClicked = false;
break;
case R.id.button_seven:
if (addNumber("7")) equalClicked = false;
break;
case R.id.button_eight:
if (addNumber("8")) equalClicked = false;
break;
case R.id.button_nine:
if (addNumber("9")) equalClicked = false;
break;
case R.id.button_addition:
if (addOperand("+")) equalClicked = false;
break;
case R.id.button_subtraction:
if (addOperand("-")) equalClicked = false;
break;
case R.id.button_multiplication:
if (addOperand("x")) equalClicked = false;
break;
case R.id.button_division:
if (addOperand("u00F7")) equalClicked = false;
break;
case R.id.button_percent:
if (addOperand("%")) equalClicked = false;
break;
case R.id.button_dot:
if (addDot()) equalClicked = false;
break;
case R.id.button_parentheses:
if (addParenthesis()) equalClicked = false;
break;
case R.id.button_clear:
textViewInputNumbers.setText("");
openParenthesis = 0;
dotUsed = false;
equalClicked = false;
break;
case R.id.button_equal:
if (textViewInputNumbers.getText().toString() != null && !textViewInputNumbers.getText().toString().equals(""))
calculate(textViewInputNumbers.getText().toString());
break;
}

}

@Override
public boolean onTouch(View view, MotionEvent motionEvent)
{
switch (motionEvent.getAction())
{
case MotionEvent.ACTION_DOWN:
{
view.getBackground().setColorFilter(Color.RED, PorterDuff.Mode.SRC_ATOP);
view.invalidate();
break;
}
case MotionEvent.ACTION_UP:
{
view.getBackground().clearColorFilter();
view.invalidate();
break;
}
}
return false;
}

private boolean addDot()
{
boolean done = false;

if (textViewInputNumbers.getText().length() == 0)
{
textViewInputNumbers.setText("0.");
dotUsed = true;
done = true;
} else if (dotUsed == true)
{
} else if (defineLastCharacter(textViewInputNumbers.getText().charAt(textViewInputNumbers.getText().length() - 1) + "") == IS_OPERAND)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + "0.");
done = true;
dotUsed = true;
} else if (defineLastCharacter(textViewInputNumbers.getText().charAt(textViewInputNumbers.getText().length() - 1) + "") == IS_NUMBER)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + ".");
done = true;
dotUsed = true;
}
return done;
}

private boolean addParenthesis()
{
boolean done = false;
int operationLength = textViewInputNumbers.getText().length();

if (operationLength == 0)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + "(");
dotUsed = false;
openParenthesis++;
done = true;
} else if (openParenthesis > 0 && operationLength > 0)
{
String lastInput = textViewInputNumbers.getText().charAt(operationLength - 1) + "";
switch (defineLastCharacter(lastInput))
{
case IS_NUMBER:
textViewInputNumbers.setText(textViewInputNumbers.getText() + ")");
done = true;
openParenthesis--;
dotUsed = false;
break;
case IS_OPERAND:
textViewInputNumbers.setText(textViewInputNumbers.getText() + "(");
done = true;
openParenthesis++;
dotUsed = false;
break;
case IS_OPEN_PARENTHESIS:
textViewInputNumbers.setText(textViewInputNumbers.getText() + "(");
done = true;
openParenthesis++;
dotUsed = false;
break;
case IS_CLOSE_PARENTHESIS:
textViewInputNumbers.setText(textViewInputNumbers.getText() + ")");
done = true;
openParenthesis--;
dotUsed = false;
break;
}
} else if (openParenthesis == 0 && operationLength > 0)
{
String lastInput = textViewInputNumbers.getText().charAt(operationLength - 1) + "";
if (defineLastCharacter(lastInput) == IS_OPERAND)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + "(");
done = true;
dotUsed = false;
openParenthesis++;
} else
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + "x(");
done = true;
dotUsed = false;
openParenthesis++;
}
}
return done;
}

private boolean addOperand(String operand)
{
boolean done = false;
int operationLength = textViewInputNumbers.getText().length();
if (operationLength > 0)
{
String lastInput = textViewInputNumbers.getText().charAt(operationLength - 1) + "";

if ((lastInput.equals("+") || lastInput.equals("-") || lastInput.equals("*") || lastInput.equals("u00F7") || lastInput.equals("%")))
{
Toast.makeText(getApplicationContext(), "Wrong format", Toast.LENGTH_LONG).show();
} else if (operand.equals("%") && defineLastCharacter(lastInput) == IS_NUMBER)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + operand);
dotUsed = false;
equalClicked = false;
lastExpression = "";
done = true;
} else if (!operand.equals("%"))
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + operand);
dotUsed = false;
equalClicked = false;
lastExpression = "";
done = true;
}
} else
{
Toast.makeText(getApplicationContext(), "Wrong Format. Operand Without any numbers?", Toast.LENGTH_LONG).show();
}
return done;
}

private boolean addNumber(String number)
{
boolean done = false;
int operationLength = textViewInputNumbers.getText().length();
if (operationLength > 0)
{
String lastCharacter = textViewInputNumbers.getText().charAt(operationLength - 1) + "";
int lastCharacterState = defineLastCharacter(lastCharacter);

if (operationLength == 1 && lastCharacterState == IS_NUMBER && lastCharacter.equals("0"))
{
textViewInputNumbers.setText(number);
done = true;
} else if (lastCharacterState == IS_OPEN_PARENTHESIS)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + number);
done = true;
} else if (lastCharacterState == IS_CLOSE_PARENTHESIS || lastCharacter.equals("%"))
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + "x" + number);
done = true;
} else if (lastCharacterState == IS_NUMBER || lastCharacterState == IS_OPERAND || lastCharacterState == IS_DOT)
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + number);
done = true;
}
} else
{
textViewInputNumbers.setText(textViewInputNumbers.getText() + number);
done = true;
}
return done;
}


private void calculate(String input)
{
String result = "";
try
{
String temp = input;
if (equalClicked)
{
temp = input + lastExpression;
} else
{
saveLastExpression(input);
}
result = scriptEngine.eval(temp.replaceAll("%", "/100").replaceAll("x", "*").replaceAll("[^\x00-\x7F]", "/")).toString();
BigDecimal decimal = new BigDecimal(result);
result = decimal.setScale(8, BigDecimal.ROUND_HALF_UP).toPlainString();
equalClicked = true;

} catch (Exception e)
{
Toast.makeText(getApplicationContext(), "Wrong Format", Toast.LENGTH_SHORT).show();
return;
}

if (result.equals("Infinity"))
{
Toast.makeText(getApplicationContext(), "Division by zero is not allowed", Toast.LENGTH_SHORT).show();
textViewInputNumbers.setText(input);

} else if (result.contains("."))
{
result = result.replaceAll("\.?0*$", "");
textViewInputNumbers.setText(result);
}
}

private void saveLastExpression(String input)
{
String lastOfExpression = input.charAt(input.length() - 1) + "";
if (input.length() > 1)
{
if (lastOfExpression.equals(")"))
{
lastExpression = ")";
int numberOfCloseParenthesis = 1;

for (int i = input.length() - 2; i >= 0; i--)
{
if (numberOfCloseParenthesis > 0)
{
String last = input.charAt(i) + "";
if (last.equals(")"))
{
numberOfCloseParenthesis++;
} else if (last.equals("("))
{
numberOfCloseParenthesis--;
}
lastExpression = last + lastExpression;
} else if (defineLastCharacter(input.charAt(i) + "") == IS_OPERAND)
{
lastExpression = input.charAt(i) + lastExpression;
break;
} else
{
lastExpression = "";
}
}
} else if (defineLastCharacter(lastOfExpression + "") == IS_NUMBER)
{
lastExpression = lastOfExpression;
for (int i = input.length() - 2; i >= 0; i--)
{
String last = input.charAt(i) + "";
if (defineLastCharacter(last) == IS_NUMBER || defineLastCharacter(last) == IS_DOT)
{
lastExpression = last + lastExpression;
} else if (defineLastCharacter(last) == IS_OPERAND)
{
lastExpression = last + lastExpression;
break;
}
if (i == 0)
{
lastExpression = "";
}
}
}
}
}

private int defineLastCharacter(String lastCharacter)
{
try
{
Integer.parseInt(lastCharacter);
return IS_NUMBER;
} catch (NumberFormatException e)
{
}

if ((lastCharacter.equals("+") || lastCharacter.equals("-") || lastCharacter.equals("x") || lastCharacter.equals("u00F7") || lastCharacter.equals("%")))
return IS_OPERAND;

if (lastCharacter.equals("("))
return IS_OPEN_PARENTHESIS;

if (lastCharacter.equals(")"))
return IS_CLOSE_PARENTHESIS;

if (lastCharacter.equals("."))
return IS_DOT;

return -1;
}



}






<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_marginTop="0.5dp"
tools:context="projects.eloy.zone.androidtestproject.MainActivity">


<LinearLayout
android:layout_marginTop="0.1dp"
android:layout_marginLeft="0.9dp"
android:layout_marginRight="0.1dp"
android:background="@android:color/black"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="3">

<TextView
android:id="@+id/textView_input_numbers"
android:layout_marginTop="25dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:gravity="end"
android:textColor="@android:color/holo_red_light"
android:textSize="40sp" />

</LinearLayout>


<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:orientation="horizontal">

<Button
android:id="@+id/button_clear"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginTop="0.1dp"
android:layout_marginLeft="0.9dp"
android:layout_marginRight="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="C"
android:textColor="@android:color/holo_red_light"
android:textSize="30sp" />

<Button
android:id="@+id/button_parentheses"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginTop="0.1dp"
android:layout_marginRight="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="( )"
android:textColor="@android:color/holo_red_light"
android:textSize="30sp" />

<Button
android:id="@+id/button_percent"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="%"
android:textColor="@android:color/holo_red_light"
android:textSize="30sp" />

<Button
android:id="@+id/button_division"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginTop="0.1dp"
android:layout_marginRight="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="u00F7"
android:textColor="@android:color/holo_red_light"
android:textSize="40sp" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">

<Button
android:id="@+id/button_seven"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginLeft="0.9dp"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="7"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_eight"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="8"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_nine"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="9"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_multiplication"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="x"
android:textColor="@android:color/holo_red_light"
android:textSize="30sp" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:orientation="horizontal">

<Button
android:id="@+id/button_four"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginLeft="0.9dp"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="4"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_five"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="5"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_six"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="6"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_subtraction"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="-"
android:textColor="@android:color/holo_red_light"
android:textSize="40sp" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:orientation="horizontal">

<Button
android:id="@+id/button_one"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginLeft="0.9dp"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="1"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_two"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="2"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_three"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="3"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_addition"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="+"
android:textColor="@android:color/holo_red_light"
android:textSize="40sp" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:orientation="horizontal">

<Button
android:id="@+id/button_zero"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginBottom="0.1dp"
android:layout_marginLeft="0.9dp"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="2"
android:background="@android:color/black"
android:text="0"
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_dot"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginBottom="0.1dp"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/black"
android:text="."
android:textColor="@android:color/white"
android:textSize="30sp" />

<Button
android:id="@+id/button_equal"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginBottom="0.1dp"
android:layout_marginRight="0.1dp"
android:layout_marginTop="0.1dp"
android:layout_weight="1"
android:background="@android:color/holo_red_dark"
android:text="="
android:textColor="@android:color/white"
android:textSize="40sp" />
</LinearLayout>


</LinearLayout>