Android Blogs: Calculator demo

You can download demo from : "http://www.codeproject.com/Articles/104931/Introduction-to-Android-development-TouchCalculato"

OR
==
1)Create java file KeypadAdapter.java
==========================
package com.pragmatouch.calculator;

import android.widget.*;
import android.content.*;
import android.view.*;
import android.view.View.OnClickListener;

public class KeypadAdapter extends BaseAdapter {
private Context mContext;

// Declare button click listener variable
private OnClickListener mOnButtonClick;

public KeypadAdapter(Context c) {
mContext = c;
}

// Method to set button click listener variable
public void setOnButtonClickListener(OnClickListener listener) {
mOnButtonClick = listener;
}

public int getCount() {
return mButtons.length;
}

public Object getItem(int position) {
return mButtons[position];
}

public long getItemId(int position) {
return 0;
}

// create a new ButtonView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
Button btn;
if (convertView == null) { // if it's not recycled, initialize some
// attributes

btn = new Button(mContext);
KeypadButton keypadButton = mButtons[position];

switch(keypadButton.mCategory)
{
case MEMORYBUFFER:
btn.setBackgroundResource(R.drawable.keypadmembuffer1);
break;
case CLEAR:
btn.setBackgroundResource(R.drawable.keypadclear1);
break;
case NUMBER:
btn.setBackgroundResource(R.drawable.keypad1);
break;
case OPERATOR:

btn.setBackgroundResource(R.drawable.keypadop1);
break;
case OTHER:
btn.setBackgroundResource(R.drawable.keypadother1);
break;
case RESULT:
btn.setBackgroundResource(R.drawable.keypadresult1);
break;
case DUMMY:
btn.setBackgroundResource(R.drawable.appvertical1);
break;
default:
btn.setBackgroundResource(R.drawable.keypad1);
break;
}
// Set OnClickListener of the button to mOnButtonClick
if(keypadButton != KeypadButton.DUMMY)
btn.setOnClickListener(mOnButtonClick);
else
btn.setClickable(false);
// Set CalculatorButton enumeration as tag of the button so that we
// will use this information from our main view to identify what to do
btn.setTag(keypadButton);
} else {
btn = (Button) convertView;
}

btn.setText(mButtons[position].getText());
return btn;
}

// Create and populate keypad buttons array with CalculatorButton enum
// values
private KeypadButton[] mButtons = { KeypadButton.MC, KeypadButton.MR,KeypadButton.MS, KeypadButton.M_ADD, KeypadButton.M_REMOVE,
KeypadButton.BACKSPACE, KeypadButton.CE, KeypadButton.C,KeypadButton.SIGN, KeypadButton.SQRT,
KeypadButton.SEVEN,KeypadButton.EIGHT, KeypadButton.NINE, KeypadButton.DIV,KeypadButton.PERCENT,
KeypadButton.FOUR, KeypadButton.FIVE,KeypadButton.SIX, KeypadButton.MULTIPLY, KeypadButton.RECIPROC,
KeypadButton.ONE, KeypadButton.TWO, KeypadButton.THREE,KeypadButton.MINUS, KeypadButton.DECIMAL_SEP,
KeypadButton.DUMMY, KeypadButton.ZERO,KeypadButton.DUMMY,KeypadButton.PLUS, KeypadButton.CALCULATE };

}

2)KeypadButton.java

===============

package com.pragmatouch.calculator;

public enum KeypadButton {

MC("MC",KeypadButtonCategory.MEMORYBUFFER)

, MR("MR",KeypadButtonCategory.MEMORYBUFFER)

, MS("MS",KeypadButtonCategory.MEMORYBUFFER)

, M_ADD("M+",KeypadButtonCategory.MEMORYBUFFER)

, M_REMOVE("M-",KeypadButtonCategory.MEMORYBUFFER)

, BACKSPACE("<-",KeypadButtonCategory.CLEAR)

, CE("CE",KeypadButtonCategory.CLEAR)

, C("C",KeypadButtonCategory.CLEAR)

, ZERO("0",KeypadButtonCategory.NUMBER)

, ONE("1",KeypadButtonCategory.NUMBER)

, TWO("2",KeypadButtonCategory.NUMBER)

, THREE("3",KeypadButtonCategory.NUMBER)

, FOUR("4",KeypadButtonCategory.NUMBER)

, FIVE("5",KeypadButtonCategory.NUMBER)

, SIX("6",KeypadButtonCategory.NUMBER)

, SEVEN("7",KeypadButtonCategory.NUMBER)

, EIGHT("8",KeypadButtonCategory.NUMBER)

, NINE("9",KeypadButtonCategory.NUMBER)

, PLUS(" + ",KeypadButtonCategory.OPERATOR)

, MINUS(" - ",KeypadButtonCategory.OPERATOR)

, MULTIPLY(" * ",KeypadButtonCategory.OPERATOR)

, DIV(" / ",KeypadButtonCategory.OPERATOR)

, RECIPROC("1/x",KeypadButtonCategory.OTHER)

, DECIMAL_SEP(",",KeypadButtonCategory.OTHER)

, SIGN("±",KeypadButtonCategory.OTHER)

, SQRT("SQRT",KeypadButtonCategory.OTHER)

, PERCENT("%",KeypadButtonCategory.OTHER)

, CALCULATE("=",KeypadButtonCategory.RESULT)

, DUMMY("",KeypadButtonCategory.DUMMY);

CharSequence mText; // Display Text

KeypadButtonCategory mCategory;

KeypadButton(CharSequence text,KeypadButtonCategory category) {

mText = text;

mCategory = category;

}

public CharSequence getText() {

return mText;

}

3)Create java file KeypadButtonCategory.java

================================

package com.pragmatouch.calculator;

public enum KeypadButtonCategory {

MEMORYBUFFER

, NUMBER

, OPERATOR

, DUMMY

, CLEAR

, RESULT

, OTHER

}

4) create java file main.java

==================

package com.pragmatouch.calculator;

import java.text.DecimalFormat;

import java.text.NumberFormat;

import java.util.Iterator;

import java.util.Stack;

import android.app.Activity;

import android.os.Bundle;

import android.widget.AdapterView;

import android.widget.Button;

import android.widget.TextView;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.GridView;

import android.view.View;

import android.view.View.OnClickListener;

public class main extends Activity {

GridView mKeypadGrid;

TextView userInputText;

TextView memoryStatText;

Stack<String> mInputStack;

Stack<String> mOperationStack;

KeypadAdapter mKeypadAdapter;

TextView mStackText;

boolean resetInput = false;

boolean hasFinalResult = false;

String mDecimalSeperator;

double memoryValue = Double.NaN;

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

DecimalFormat currencyFormatter = (DecimalFormat) NumberFormat

.getInstance();

char decimalSeperator = currencyFormatter.getDecimalFormatSymbols()

.getDecimalSeparator();

mDecimalSeperator = Character.toString(decimalSeperator);

setContentView(R.layout.main);

// Create the stack

mInputStack = new Stack<String>();

mOperationStack = new Stack<String>();

// Get reference to the keypad button GridView

mKeypadGrid = (GridView) findViewById(R.id.grdButtons);

// Get reference to the user input TextView

userInputText = (TextView) findViewById(R.id.txtInput);

userInputText.setText("0");

memoryStatText = (TextView) findViewById(R.id.txtMemory);

memoryStatText.setText("");

mStackText = (TextView) findViewById(R.id.txtStack);

// Create Keypad Adapter

mKeypadAdapter = new KeypadAdapter(this);

// Set adapter of the keypad grid

mKeypadGrid.setAdapter(mKeypadAdapter);

// Set button click listener of the keypad adapter

mKeypadAdapter.setOnButtonClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

Button btn = (Button) v;

// Get the KeypadButton value which is used to identify the

// keypad button from the Button's tag

KeypadButton keypadButton = (KeypadButton) btn.getTag();

// Process keypad button

ProcessKeypadInput(keypadButton);

}

});

mKeypadGrid.setOnItemClickListener(new OnItemClickListener() {

public void onItemClick(AdapterView<?> parent, View v,

int position, long id) {

}

});

}

private void ProcessKeypadInput(KeypadButton keypadButton) {

//Toast.makeText(this, keypadButton.getText(), Toast.LENGTH_SHORT).show();

String text = keypadButton.getText().toString();

String currentInput = userInputText.getText().toString();

int currentInputLen = currentInput.length();

String evalResult = null;

double userInputValue = Double.NaN;

switch (keypadButton) {

case BACKSPACE: // Handle backspace

// If has operand skip backspace

if (resetInput)

return;

int endIndex = currentInputLen - 1;

// There is one character at input so reset input to 0

if (endIndex < 1) {

userInputText.setText("0");

}

// Trim last character of the input text

else {

userInputText.setText(currentInput.subSequence(0, endIndex));

}

break;

case SIGN: // Handle -/+ sign

// input has text and is different than initial value 0

if (currentInputLen > 0 && currentInput != "0") {

// Already has (-) sign. Remove that sign

if (currentInput.charAt(0) == '-') {

userInputText.setText(currentInput.subSequence(1,

currentInputLen));

}

// Prepend (-) sign

else {

userInputText.setText("-" + currentInput.toString());

}

break;

case CE: // Handle clear input

userInputText.setText("0");

break;

case C: // Handle clear input and stack

userInputText.setText("0");

clearStacks();

break;

case DECIMAL_SEP: // Handle decimal seperator

if (hasFinalResult || resetInput) {

userInputText.setText("0" + mDecimalSeperator);

hasFinalResult = false;

resetInput = false;

} else if (currentInput.contains("."))

return;

else

userInputText.append(mDecimalSeperator);

break;

case DIV:

case PLUS:

case MINUS:

case MULTIPLY:

if (resetInput) {

mInputStack.pop();

mOperationStack.pop();

} else {

if (currentInput.charAt(0) == '-') {

mInputStack.add("(" + currentInput + ")");

} else {

mInputStack.add(currentInput);

}

mOperationStack.add(currentInput);

}

mInputStack.add(text);

mOperationStack.add(text);

dumpInputStack();

evalResult = evaluateResult(false);

if (evalResult != null)

userInputText.setText(evalResult);

resetInput = true;

break;

case CALCULATE:

if (mOperationStack.size() == 0)

break;

mOperationStack.add(currentInput);

evalResult = evaluateResult(true);

if (evalResult != null) {

clearStacks();

userInputText.setText(evalResult);

resetInput = false;

hasFinalResult = true;

}

break;

case M_ADD: // Add user input value to memory buffer

userInputValue = tryParseUserInput();

if (Double.isNaN(userInputValue))

return;

if (Double.isNaN(memoryValue))

memoryValue = 0;

memoryValue += userInputValue;

displayMemoryStat();

hasFinalResult = true;

break;

case M_REMOVE: // Subtract user input value to memory buffer

userInputValue = tryParseUserInput();

if (Double.isNaN(userInputValue))

return;

if (Double.isNaN(memoryValue))

memoryValue = 0;

memoryValue -= userInputValue;

displayMemoryStat();

hasFinalResult = true;

break;

case MC: // Reset memory buffer to 0

memoryValue = Double.NaN;

displayMemoryStat();

break;

case MR: // Read memoryBuffer value

if (Double.isNaN(memoryValue))

return;

userInputText.setText(doubleToString(memoryValue));

displayMemoryStat();

break;

case MS: // Set memoryBuffer value to user input

userInputValue = tryParseUserInput();

if (Double.isNaN(userInputValue))

return;

memoryValue = userInputValue;

displayMemoryStat();

hasFinalResult = true;

break;

default:

if (Character.isDigit(text.charAt(0))) {

if (currentInput.equals("0") || resetInput || hasFinalResult) {

userInputText.setText(text);

resetInput = false;

hasFinalResult = false;

} else {

userInputText.append(text);

resetInput = false;

}

break;

}

private void clearStacks() {

mInputStack.clear();

mOperationStack.clear();

mStackText.setText("");

}

private void dumpInputStack() {

Iterator<String> it = mInputStack.iterator();

StringBuilder sb = new StringBuilder();

while (it.hasNext()) {

CharSequence iValue = it.next();

sb.append(iValue);

}

mStackText.setText(sb.toString());

}

private String evaluateResult(boolean requestedByUser) {

if ((!requestedByUser && mOperationStack.size() != 4)

|| (requestedByUser && mOperationStack.size() != 3))

return null;

String left = mOperationStack.get(0);

String operator = mOperationStack.get(1);

String right = mOperationStack.get(2);

String tmp = null;

if (!requestedByUser)

tmp = mOperationStack.get(3);

double leftVal = Double.parseDouble(left.toString());

double rightVal = Double.parseDouble(right.toString());

double result = Double.NaN;

if (operator.equals(KeypadButton.DIV.getText())) {

result = leftVal / rightVal;

} else if (operator.equals(KeypadButton.MULTIPLY.getText())) {

result = leftVal * rightVal;

} else if (operator.equals(KeypadButton.PLUS.getText())) {

result = leftVal + rightVal;

} else if (operator.equals(KeypadButton.MINUS.getText())) {

result = leftVal - rightVal;

}

String resultStr = doubleToString(result);

if (resultStr == null)

return null;

mOperationStack.clear();

if (!requestedByUser) {

mOperationStack.add(resultStr);

mOperationStack.add(tmp);

}

return resultStr;

}

private String doubleToString(double value) {

if (Double.isNaN(value))

return null;

long longVal = (long) value;

if (longVal == value)

return Long.toString(longVal);

else

return Double.toString(value);

}

private double tryParseUserInput() {

String inputStr = userInputText.getText().toString();

double result = Double.NaN;

try {

result = Double.parseDouble(inputStr);

} catch (NumberFormatException nfe) {

}

return result;

}

private void displayMemoryStat() {

if (Double.isNaN(memoryValue)) {

memoryStatText.setText("");

} else {

memoryStatText.setText("M = " + doubleToString(memoryValue));

}

5)main.xml

========

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:background="@drawable/appvertical1" >

<TextView

android:id="@+id/txtStack"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:textSize="15sp"

android:gravity="right"

android:background="@drawable/stackview1"

android:layout_marginTop = "3sp"

android:layout_marginLeft = "5sp"

android:layout_marginRight = "5sp"

android:textColor="@color/darkgrey"/>

<TextView

android:id="@+id/txtInput"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:textSize="25sp"

android:gravity="right"

android:background="@drawable/inputview1"

android:textColor="@color/darkgreen"

android:layout_marginLeft = "5sp"

android:layout_marginRight = "5sp"/>

<TextView

android:id="@+id/txtMemory"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:textSize="15sp"

android:textColor="@color/lightyellow"

android:gravity="left"

android:layout_marginLeft = "5sp"

android:layout_marginRight = "5sp"/>

<GridView

android:id="@+id/grdButtons"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:columnWidth="90dp"

android:numColumns="5"

android:verticalSpacing="10dp"

android:horizontalSpacing="10dp"

android:stretchMode="columnWidth"

android:gravity="center"/>

</LinearLayout>

6)manifest.xml

==========

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.pragmatouch.calculator"

android:versionCode="1"

android:versionName="1.0">

<activity android:name=".main"

android:label="@string/app_name">

<intent-filter>

</intent-filter>

</activity>

</application>

<uses-sdk android:minSdkVersion="8" />

</manifest>

Android Blogs

Tuesday 25 March 2014

Calculator demo

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