I was looking for a review on my coding. Since I'm planning to get a job as a Android Programmer in the long run.
This is my first calculator app, which I did by self learning Programming. I have no other Programming Langauge experience.
So I would love to hear how bad my coding is? Which areas I need improving on? What I should have used instead of repeating my self, which is bad coding as I understand.
private Button btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btnZero, btnDoubleZero, btnEqual, btnMultiply, btnDevide,
btnPlus, btnMinus, btnClean, btnPoint;
private TextView textView1, totalSum;
private String lastInputNumber = "";
private double num1 = 0;
private double num2 = 0;
private double tempCount = 0;
private double tempSum = 0;
private int myClickCount = 0;
private boolean nSwitch = true;
private boolean equalSwitch = false;
String stringMinus = " - ";
String[] operation = {
};
String[] lastNumber = {
};
ArrayList<String> op = new ArrayList<String>();
ArrayList<String> ln = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn1 = (Button) findViewById(R.id.button3);
btn2 = (Button) findViewById(R.id.button7);
btn3 = (Button) findViewById(R.id.button11);
btn4 = (Button) findViewById(R.id.button2);
btn5 = (Button) findViewById(R.id.button6);
btn6 = (Button) findViewById(R.id.button10);
btn7 = (Button) findViewById(R.id.button1);
btn8 = (Button) findViewById(R.id.button5);
btn9 = (Button) findViewById(R.id.button9);
btnZero = (Button) findViewById(R.id.button4);
btnDoubleZero = (Button) findViewById(R.id.button8);
btnEqual = (Button) findViewById(R.id.button20);
btnMultiply = (Button) findViewById(R.id.button14);
btnDevide = (Button) findViewById(R.id.button13);
btnPlus = (Button) findViewById(R.id.button16);
btnMinus = (Button) findViewById(R.id.button15);
btnClean = (Button) findViewById(R.id.button19);
btnPoint = (Button) findViewById(R.id.button12);
btn1.setOnClickListener(this);
btn2.setOnClickListener(this);
btn3.setOnClickListener(this);
btn4.setOnClickListener(this);
btn5.setOnClickListener(this);
btn6.setOnClickListener(this);
btn7.setOnClickListener(this);
btn8.setOnClickListener(this);
btn9.setOnClickListener(this);
btnZero.setOnClickListener(this);
btnDoubleZero.setOnClickListener(this);
btnEqual.setOnClickListener(this);
btnMultiply.setOnClickListener(this);
btnDevide.setOnClickListener(this);
btnPlus.setOnClickListener(this);
btnMinus.setOnClickListener(this);
btnClean.setOnClickListener(this);
btnPoint.setOnClickListener(this);
textView1 = (TextView) findViewById(R.id.textView1);
totalSum = (TextView) findViewById(R.id.textView3);
Typeface tf = Typeface.createFromAsset(getAssets(), "fonts/Roboto-Light.ttf");
textView1.setTypeface(tf);
totalSum.setTypeface(tf);
Typeface btnTf = Typeface.createFromAsset(getAssets(), "fonts/Roboto-Light.ttf");
btnMultiply.setTypeface(btnTf);
btnDevide.setTypeface(btnTf);
btnEqual.setTypeface(btnTf);
btnClean.setTypeface(btnTf);
btnMinus.setTypeface(btnTf);
btnPlus.setTypeface(btnTf);
btnZero.setTypeface(btnTf);
btnDoubleZero.setTypeface(btnTf);
btn1.setTypeface(btnTf);
btn2.setTypeface(btnTf);
btn3.setTypeface(btnTf);
btn4.setTypeface(btnTf);
btn5.setTypeface(btnTf);
btn6.setTypeface(btnTf);
btn7.setTypeface(btnTf);
btn8.setTypeface(btnTf);
btn9.setTypeface(btnTf);
// makes the textviews scrollable
textView1.setMovementMethod(new ScrollingMovementMethod());
totalSum.setMovementMethod(new ScrollingMovementMethod());
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button3:
// log that you clicked one
Log.d("OSSI", "button 1 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add one to the existing textView1 string
textView1.setText(textView1.getText().toString() + "1");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button7:
// log that you clicked two
Log.d("OSSI", "button 2 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add two to the existing textView1 string
textView1.setText(textView1.getText().toString() + "2");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button11:
// log that you clicked three
Log.d("OSSI", "button 3 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add three to the existing textView1 string
textView1.setText(textView1.getText().toString() + "3");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button2:
// log that you clicked four
Log.d("OSSI", "button 4 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add four to the existing textView1 string
textView1.setText(textView1.getText().toString() + "4");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button6:
// log that you clicked five
Log.d("OSSI", "button 5 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add five to the existing textView1 string
textView1.setText(textView1.getText().toString() + "5");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button10:
// log that you clicked six
Log.d("OSSI", "button 6 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add six to the existing textView1 string
textView1.setText(textView1.getText().toString() + "6");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button1:
// log that you clicked seven
Log.d("OSSI", "button 7 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add seven to the existing textView1 string
textView1.setText(textView1.getText().toString() + "7");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button5:
// log that you clicked eight
Log.d("OSSI", "button 8 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add eight to the existing textView1 string
textView1.setText(textView1.getText().toString() + "8");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button9:
// log that you clicked nine
Log.d("OSSI", "button 9 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add nine to the existing textView1 string
textView1.setText(textView1.getText().toString() + "9");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button4:
// log that you clicked zero
Log.d("OSSI", "button 0 was clicked");
// First if switch is to check of equal was used
if (equalSwitch == true) {
} else {
// add zero to the existing textView1 string
textView1.setText(textView1.getText().toString() + "0");
// my click counter plus one
myClickCount++;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button8:
// log that you clicked doublezero
Log.d("OSSI", "button 00 was clicked");
if (myClickCount == 0) {
}
else if (equalSwitch == true) {
}
else {
// add doublezero to the existing textView1
textView1.setText(textView1.getText().toString() + "00");
// my click counter plus one
myClickCount += 2;
// Bollean switch so operators cant be called twice
nSwitch = false;
}
break;
case R.id.button13:
Log.d("OSSI", "button / was clicked");
// checks if ln arraylist has something stored before executing the math code
if (textView1.length() < 1) {
}
else if (ln.isEmpty()) {
// Log ln array is Empty
Log.d("OSSI", "ln is empty");
// Getting textView1 and parse into an int
num1 = Double.parseDouble(textView1.getText().toString());
// Saving the int num1 in sum1 as a String
String sum1 = Double.toString(num1);
// Setting text from sum1 to totalSum
totalSum.setText(sum1);
// Adding sum1 inside ln string arraylist
ln.add(sum1);
// Adding devide symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + " / ");
// Adding devide to the op array list
op.add("/");
}
else if (nSwitch == true) {
// Save textView1 into lastOperator String
String lastOperator = textView1.getText().toString();
// Save String without the last Operator
String deleteLastOperator = lastOperator.substring(lastOperator.length() - (lastOperator.length()),
lastOperator.length() - 3);
// Saving the new String without the last Operator
textView1.setText(deleteLastOperator);
// Adding new operator to textView1 String
textView1.setText(textView1.getText().toString() + " / ");
// Adding to the op array list
op.add("/");
// Removes the first operator from op arraylist
op.remove(0);
}
else {
// Saving textView1 as lastNumb
String lastNumb = textView1.getText().toString();
// A substring of lastNumb String will be saved as lastIput
// (lastnumb minus the click counter, till the last lastnumb)
String lastInput = lastNumb.substring(lastNumb.length() - myClickCount, lastNumb.length());
// Parsing lastInput to into num2 integer
num2 = Double.parseDouble(lastInput);
// Parsing String of totalSum into tempSum integer
tempSum = Double.parseDouble(totalSum.getText().toString());
if (op.get(0) == "+") {
Log.d("OSSI", "if plus operator worked");
// Calculating tempSum + sum2
tempSum = tempSum + num2;
}
else if (op.get(0) == "-") {
Log.d("OSSI", "if minus operator worked");
// Calculating tempSum - sum2
tempSum = tempSum - num2;
}
else if (op.get(0) == "/") {
Log.d("OSSI", "if devide operator worked");
// Calculating tempSum / sum2
tempSum = tempSum / num2;
}
else if (op.get(0) == "*") {
Log.d("OSSI", "if multiply operator worked");
// Calculating tempSum * sum2
tempSum = tempSum * num2;
}
// Math to round 2 decimal number before tempSum will be set into totalSum
double mathRound = tempSum;
double tempSum = Math.round(mathRound*100.0)/100.0;
// Changing tempSum to a String
String sumDevide = Double.toString(tempSum);
// String sumDevide will be the new totalSum text
totalSum.setText(sumDevide);
// Adding devide symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + " / ");
// Adding to the op array list
op.add("/");
// Removes the first operator from op arraylist
op.remove(0);
}
// my click counter reset to zero
myClickCount = 0;
// Equal Switch to false so numbers can be used again
equalSwitch = false;
nSwitch = true;
break;
case R.id.button14:
Log.d("OSSI", "button * was clicked");
if (textView1.length() < 1) {
}
// checks if ln arraylist has something stored before executing the math code
else if (ln.isEmpty()) {
// Log ln array is Empty
Log.d("OSSI", "ln is empty");
// Getting textView1 and parse into an int
num1 = Double.parseDouble(textView1.getText().toString());
// Saving the int num1 in sum1 as a String
String sum1 = Double.toString(num1);
// Setting text from sum1 to totalSum
totalSum.setText(sum1);
// Adding sum1 inside ln string arraylist
ln.add(sum1);
// Adding multiply symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + " * ");
// Adding multiply to the op array list
op.add("*");
}
else if (nSwitch == true) {
// Save textView1 into lastOperator String
String lastOperator = textView1.getText().toString();
// Save String without the last Operator
String deleteLastOperator = lastOperator.substring(lastOperator.length() - (lastOperator.length()),
lastOperator.length() - 3);
// Saving the new String without the last Operator
textView1.setText(deleteLastOperator);
// Adding new operator to textView1 String
textView1.setText(textView1.getText().toString() + " * ");
// Adding to the op array list
op.add("*");
// Removes the first operator from op arraylist
op.remove(0);
}
else {
// Saving textView1 as lastNumb
String lastNumb = textView1.getText().toString();
// A substring of lastNumb String will be saved as lastIput
// (lastnumb minus the click counter, till the last lastnumb)
String lastInput = lastNumb.substring(lastNumb.length() - myClickCount, lastNumb.length());
// Parsing lastInput to into num2 integer
num2 = Double.parseDouble(lastInput);
// Parsing String of totalSum into tempSum integer
tempSum = Double.parseDouble(totalSum.getText().toString());
if (op.get(0) == "+") {
Log.d("OSSI", "if plus operator worked");
// Calculating tempSum + sum2
tempSum = tempSum + num2;
}
else if (op.get(0) == "-") {
Log.d("OSSI", "if minus operator worked");
// Calculating tempSum - sum2
tempSum = tempSum - num2;
}
else if (op.get(0) == "/") {
Log.d("OSSI", "if devide operator worked");
// Calculating tempSum / sum2
tempSum = tempSum / num2;
}
else if (op.get(0) == "*") {
Log.d("OSSI", "if multiply operator worked");
// Calculating tempSum * sum2
tempSum = tempSum * num2;
}
// Math to round 2 decimal number before tempSum will be set into totalSum
double mathRound = tempSum;
double tempSum = Math.round(mathRound*100.0)/100.0;
// Changing tempSum to a String
String sumMulitply = Double.toString(tempSum);
// String sumMultiply will be the new totalSum text
totalSum.setText(sumMulitply);
// Adding multiply symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + " * ");
// Adding to the op array list
op.add("*");
// Removes the first operator from op arraylist
op.remove(0);
}
// my click counter reset to zero
myClickCount = 0;
nSwitch = true;
// Equal Switch to false so numbers can be used again
equalSwitch = false;
break;
case R.id.button15:
Log.d("OSSI", "button - was clicked");
if (textView1.length() < 1) {
}
// checks if ln arraylist has something stored before executing the math code
else if (ln.isEmpty()) {
// Log ln array is Empty
Log.d("OSSI", "ln is empty");
// Getting textView1 and parse into an int
num1 = Double.parseDouble(textView1.getText().toString());
// Saving the int num1 in sum1 as a String
String sum1 = Double.toString(num1);
// Setting text from sum1 to totalSum
totalSum.setText(sum1);
// Adding sum1 inside ln string arraylist
ln.add(sum1);
// Adding minus symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + stringMinus);
// Adding minus to the op array list
op.add("-");
}
else if (nSwitch == true) {
// Save textView1 into lastOperator String
String lastOperator = textView1.getText().toString();
// Save String without the last Operator
String deleteLastOperator = lastOperator.substring(lastOperator.length() - (lastOperator.length()),
lastOperator.length() - 3);
// Saving the new String without the last Operator
textView1.setText(deleteLastOperator);
// Adding new operator to textView1 String
textView1.setText(textView1.getText().toString() + stringMinus);
// Adding to the op array list
op.add("-");
// Removes the first operator from op arraylist
op.remove(0);
}
else {
// Saving textView1 as lastNumb
String lastNumb = textView1.getText().toString();
// A substring of lastNumb String will be saved as lastIput
// (lastnumb minus the click counter, till the last lastnumb)
String lastInput = lastNumb.substring(lastNumb.length() - myClickCount, lastNumb.length());
// Parsing lastInput to into num2 integer
num2 = Double.parseDouble(lastInput);
// Parsing String of totalSum into tempSum integer
tempSum = Double.parseDouble(totalSum.getText().toString());
if (op.get(0) == "+") {
Log.d("OSSI", "if plus operator worked");
// Calculating tempSum + sum2
tempSum = tempSum + num2;
}
else if (op.get(0) == "-") {
Log.d("OSSI", "if minus operator worked");
// Calculating tempSum - sum2
tempSum = tempSum - num2;
}
else if (op.get(0) == "/") {
Log.d("OSSI", "if devide operator worked");
// Calculating tempSum / sum2
tempSum = tempSum / num2;
}
else if (op.get(0) == "*") {
Log.d("OSSI", "if multiply operator worked");
// Calculating tempSum * sum2
tempSum = tempSum * num2;
}
// Math to round 2 decimal number before tempSum will be set into totalSum
double mathRound = tempSum;
double tempSum = Math.round(mathRound*100.0)/100.0;
// Changing tempSum to a String
String sumMinus = Double.toString(tempSum);
// String sumMinus will be the new totalSum text
totalSum.setText(sumMinus);
// Adding multiply symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + stringMinus);
// Adding to the op array list
op.add("-");
// Removes the first operator from op arraylist
op.remove(0);
}
// my click counter reset to zero
myClickCount = 0;
nSwitch = true;
// Equal Switch to false so numbers can be used again
equalSwitch = false;
break;
case R.id.button16:
Log.d("OSSI", "button + was clicked");
if (textView1.length() < 1) {
}
// checks if ln arraylist has something stored before executing the math code
else if (ln.isEmpty()) {
// Log ln array is Empty
Log.d("OSSI", "ln is empty");
// Getting textView1 and parse into an int
num1 = Double.parseDouble(textView1.getText().toString());
// Saving the int num1 in sum1 as a String
String sum1 = Double.toString(num1);
// Setting text from sum1 to totalSum
totalSum.setText(sum1);
// Adding sum1 inside ln string arraylist
ln.add(sum1);
// Adding plus symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + " + ");
// Adding plus to the op array list
op.add("+");
}
else if (nSwitch == true) {
// Save textView1 into lastOperator String
String lastOperator = textView1.getText().toString();
// Save String without the last Operator
String deleteLastOperator = lastOperator.substring(lastOperator.length() - (lastOperator.length()),
lastOperator.length() - 3);
// Saving the new String without the last Operator
textView1.setText(deleteLastOperator);
// Adding new operator to textView1 String
textView1.setText(textView1.getText().toString() + " + ");
// Adding to the op array list
op.add("+");
// Removes the first operator from op arraylist
op.remove(0);
}
else {
// Saving textView1 as lastNumb
String lastNumb = textView1.getText().toString();
// A substring of lastNumb String will be saved as lastIput
// (lastnumb minus the click counter, till the last lastnumb)
String lastInput = lastNumb.substring(lastNumb.length() - myClickCount, lastNumb.length());
// Parsing lastInput to into num2 integer
num2 = Double.parseDouble(lastInput);
// Parsing String of totalSum into tempSum integer
tempSum = Double.parseDouble(totalSum.getText().toString());
if (op.get(0) == "+") {
Log.d("OSSI", "if plus operator worked");
// Calculating tempSum + sum2
tempSum = tempSum + num2;
new DecimalFormat("#.##").format(tempSum);
}
else if (op.get(0) == "-") {
Log.d("OSSI", "if minus operator worked");
// Calculating tempSum - sum2
tempSum = tempSum - num2;
}
else if (op.get(0) == "/") {
Log.d("OSSI", "if devide operator worked");
// Calculating tempSum / sum2
tempSum = tempSum / num2;
}
else if (op.get(0) == "*") {
Log.d("OSSI", "if multiply operator worked");
// Calculating tempSum * sum2
tempSum = tempSum * num2;
}
// Math to round 2 decimal number before tempSum will be set into totalSum
double mathRound = tempSum;
double tempSum = Math.round(mathRound*100.0)/100.0;
// Changing tempSum to a String
String sumAdition = Double.toString(tempSum);
// String sumAdition will be the new totalSum text
totalSum.setText(sumAdition);
// Adding multiply symbol to the exsiting textView1 text
textView1.setText(textView1.getText().toString() + " + ");
// Adding to the op array list
op.add("+");
// Removes the first operator from op arraylist
op.remove(0);
}
// my click counter reset to zero
myClickCount = 0;
// Equal Switch to false so numbers can be used again
equalSwitch = false;
nSwitch = true;
break;
case R.id.button20:
Log.d("OSSI", "button = was clicked");
if (myClickCount == 0) {
}
else if (ln.isEmpty()) {
}
else if (nSwitch == true) {
}
else {
// Saving textView1 as lastNumb
String lastNumb = textView1.getText().toString();
// A substring of lastNumb String will be saved as lastIput
// (lastnumb minus the click counter, till the last lastnumb)
String lastInput = lastNumb.substring(lastNumb.length() - myClickCount, lastNumb.length());
// Parsing lastInput to into num2 integer
num2 = Double.parseDouble(lastInput);
// Parsing String of totalSum into tempSum integer
tempSum = Double.parseDouble(totalSum.getText().toString());
if (op.get(0) == "+") {
Log.d("OSSI", "if plus operator worked");
// Calculating tempSum + sum2
tempSum = tempSum + num2;
}
else if (op.get(0) == "-") {
Log.d("OSSI", "if minus operator worked");
// Calculating tempSum - sum2
tempSum = tempSum - num2;
}
else if (op.get(0) == "/") {
Log.d("OSSI", "if devide operator worked");
// Calculating tempSum / sum2
tempSum = tempSum / num2;
}
else if (op.get(0) == "*") {
Log.d("OSSI", "if multiply operator worked");
// Calculating tempSum * sum2
tempSum = tempSum * num2;
}
// Math to round 2 decimal number before tempSum will be set into totalSum
double mathRound = tempSum;
double tempSum = Math.round(mathRound*100.0)/100.0;
// Changing tempSum to a String
String sumEqual = Double.toString(tempSum);
// String sumMultiply will be the new totalSum text
totalSum.setText(sumEqual);
// Adding to the op array list
op.add("tF");
// Removes the first operator from op arraylist
op.remove(0);
// checks if equal was pressed so no number can be pressed
equalSwitch = true;
}
break;
case R.id.button12:
Log.d("OSSI", "button Point was clicked");
// sets the textView1 to a string
String string = textView1.getText().toString();
String pointChecker = string.substring(string.length() - myClickCount, string.length());
if (equalSwitch == true) {
}
else if (string.length() == 0){
// If string length is 0 no point will added
}
else if (myClickCount == 0) {
}
else if (pointChecker.contains(".")) {
// If string contains a point, no new point will added
}
else {
// Adds one point in the TextView after any given number
textView1.setText(textView1.getText().toString() + ".");
myClickCount++;
}
break;
case R.id.button19:
Log.d("OSSI", "button C was clicked");
textView1.setText("");
totalSum.setText("");
this.num1 = 0;
this.num2 = 0;
this.tempCount = 0;
this.tempSum = 0;
this.myClickCount = 0;
this.nSwitch = true;
this.equalSwitch = false;
op.removeAll(op);
ln.removeAll(ln);
break;
default:
break;
}
}
