I have to perform a pow function while getting equation from string like "2 power 3". I know there is function Math.pow(a, b) and also I can use for loop to achieve this , but the problem is both methods needs integer and I have equation in string. I don't know how to parse this string and separate both variables. And there is another problem. my equation could get little bit complex as well. for instance it could be like "2+3*5/5 power 2"
public class CalculationActivity extends AppCompatActivity {
EditText editText;
Button btnCalc;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calculation);
editText=findViewById(R.id.et_regular_dep);
btnCalc=findViewById(R.id.btnCalculate);
btnCalc.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String equation= editText.getText().toString();
CalculateResult(equation);
}
});
}
private void CalculateResult(String equation) {
// here to perform power function
}
}
Try this :
String eq = "2 power 3";
String no2 = eq.substring(eq.indexOf("power") + 6 , eq.length());
String no1 = eq.substring(0,eq.indexOf("power")-1);
Log.d("no1",no1);
Log.d("no2",no2);
Log.d("ans",Math.pow(Double.parseDouble(no1),Double.parseDouble(no2))+"");
another easy way to do it
String eq = "2 power 3";
eq = eq.trim(); // if it has extra space at the start or end
String no1 = eq.split(" ")[0];
String no2 = eq.split(" ")[2];
Log.e("no1", no1);
Log.e("no2", no2);
Log.e("ans", Math.pow(Double.parseDouble(no1), Double.parseDouble(no2)) + "");
Related
I'm working on Android Studio, to make one field calculator
It will be just one Text field, button, and another text view.
If I put "2+5*6" for example it must understand the operation.
Can anyone help me?
Check out my code please
public class MainActivity extends AppCompatActivity {
public static final String equation = "[0-9]";
String opr = " ";
int[] result;
int castedInt;
String temp;
String[] separated;
EditText txte;
TextView txtv;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void buResult(View view) {
txte = (EditText)findViewById(R.id.editText);
for (int i = 0; i < txte.length(); i++) {
if (Pattern.matches(txte.toString(), equation)) {
separated[i] = txte.toString();
temp = separated[i];
castedInt = Integer.parseInt(temp.toString());
result[i] = castedInt;
}
else {
opr = txte.toString();
}
txtv.setText(result[i] + opr + result[i]);
}
}
}
You should implement reverse polish notation for string.
Example code could be find here https://codereview.stackexchange.com/questions/120451/reverse-polish-notation-calculator-in-java
As defined in the documentation regex must be a regular expression. You need to transform the user input into a regular expression.
Pattern.matches(String regex, CharSequence input)
Also you are always using the whole user input:
separated[i] = txte.toString();
All "separated" indexes will contain the same.
If it's Ok to use language support (instead of creating algorithm from scratch) you can use like this:
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
...
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
txtv.setText(engine.eval(txte.toString()));
*credits : stackoverflow.com/a/2605051/936786
I wanted to delete the last occurrence of a function name in a calculator edittext with one click.
I already have a delete button, which looks like this:
private void onDelete() {
final Editable formulaText = mFormulaEditText.getEditableText();
final int formulaLength = formulaText.length();
if (formulaLength > 0) {
formulaText.delete(formulaLength - 1, formulaLength);
}
}
I tried to get the last 3 character than if it equals with the function name, delete 3 letters, but the problem is that there are some longer (e.g.: atanh) or shorter function names (e.g.: ln).
P. S. Sorry for my English.
You could use a regular expression:
private static String removeLastMathFunction(String input) {
final String mathFnRegex = "(ln|log|a?(sin|cos|tan)h?)";
final String lastMathFnRegex = mathFnRegex + "(?!.*" + mathFnRegex + ")";
return input.replaceAll(lastMathFnRegex, "");
}
private void onDelete() {
String oldInputValue = mFormulaEditText.getText().toString();
String newInputValue = removeLastMathFunction(oldInputValue);
mFormulaEditText.setText(newInputValue);
}
I have 2 edittexts and 1 textview. 1 edittext for input the price another one the percentage and the textview will display the result of them both (the price * percentage/100) and i want to make the 1st edittext input(for the price) will change the format of the input and display it on the same edittext with decimal format. For example :
edittext1
100
the user type 100 it will just display 100 ,but when the user type one or more number(S) it will add "," every 3 number
edittext1
1,000
edittext1
10,000
edittext1
100,000
edittext1
1,000,000
and so on
i have the functions, one will autocalculate the value for textview1 , another will convert automatically the input of edittext. However they cant work together because the format for calculation function, it uses int/long/double and for the converter it uses decimalformat . If i use them both the app will crash with javanumberformatexception unable to parse int "1,000"(if we put 1000 into edittext)
my function for autocalculate
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simulasikredit);
ethint1 = (EditText) findViewById(R.id.ethint);
etpersen2 = (EditText) findViewById(R.id.etpersen);
textvDP1 = (TextView) findViewById(R.id.textvDP);
etpersen2.addTextChangedListener(new TextWatcher() {
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String text1 = ethint1.getText().toString();
String text2 = etpersen2.getText().toString();
long input1 = 0;
long input2 = 0;
if(text1.length()>0)
input1 = Long.valueOf(text1);
if(text2.length()>0)
input2 = Long.valueOf(text2);
if (text1.length() != 0) {
long output = (input1 * input2) / 100;
textvDP1.setText(""+output);
}
else if(text2.length() == 0){
textvDP1.setText("");
}
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void afterTextChanged(Editable s) {
}
}); }
et stands for edittext, tv stands for textview
and makedecimal function
public void makedecimal(View v)
{
ethint1.setRawInputType(InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_FLAG_DECIMAL);
DigitsKeyListener dkl = new DigitsKeyListener(true,true);
ethint1.setKeyListener(dkl);
ethint1.addTextChangedListener(new TextWatcher(){
private String current = "";
#Override
public void afterTextChanged(Editable s) {
String userInput=s.toString();
if(!userInput.toString().equals(current)){
ethint1.removeTextChangedListener(this);
String cleanString = userInput.replaceAll("[,]", "");
if(cleanString.length()>0){
double parsed = Double.parseDouble(cleanString);
String formated = DecimalFormat.getNumberInstance().format(parsed);
current = formated;
ethint1.setText(formated);
ethint1.setSelection(formated.length());
}else{
ethint1.setText(cleanString);
ethint1.setSelection(cleanString.length());
}
ethint1.addTextChangedListener(this);
}
this makedecimal is android:onClick from ethint , ethint is the id(these two come from 1 edittext)
I need to fulfil a similar requirements before where we need to format the number in thousands and also support fractions.
My approach is to register a TextWatcher format text every time input changed, and provide a public method to get numeric value by stripping separators, which is quite tricky. My solution also caters for locale-specific separator by utilizing DecimalFormatSymbols class.
private final char GROUPING_SEPARATOR = DecimalFormatSymbols.getInstance().getGroupingSeparator();
private final char DECIMAL_SEPARATOR = DecimalFormatSymbols.getInstance().getDecimalSeparator();
...
/**
* Return numeric value repesented by the text field
* #return numeric value or {#link Double.NaN} if not a number
*/
public double getNumericValue() {
String original = getText().toString().replaceAll(mNumberFilterRegex, "");
if (hasCustomDecimalSeparator) {
// swap custom decimal separator with locale one to allow parsing
original = StringUtils.replace(original,
String.valueOf(mDecimalSeparator), String.valueOf(DECIMAL_SEPARATOR));
}
try {
return NumberFormat.getInstance().parse(original).doubleValue();
} catch (ParseException e) {
return Double.NaN;
}
}
/**
* Add grouping separators to string
* #param original original string, may already contains incorrect grouping separators
* #return string with correct grouping separators
*/
private String format(final String original) {
final String[] parts = original.split("\\" + mDecimalSeparator, -1);
String number = parts[0] // since we split with limit -1 there will always be at least 1 part
.replaceAll(mNumberFilterRegex, "")
.replaceFirst(LEADING_ZERO_FILTER_REGEX, "");
// only add grouping separators for non custom decimal separator
if (!hasCustomDecimalSeparator) {
// add grouping separators, need to reverse back and forth since Java regex does not support
// right to left matching
number = StringUtils.reverse(
StringUtils.reverse(number).replaceAll("(.{3})", "$1" + GROUPING_SEPARATOR));
// remove leading grouping separator if any
number = StringUtils.removeStart(number, String.valueOf(GROUPING_SEPARATOR));
}
// add fraction part if any
if (parts.length > 1) {
number += mDecimalSeparator + parts[1];
}
return number;
}
It's quite tedious to elaborate here so I'll only give a link for your own reading:
https://gist.github.com/hidroh/77ca470bbb8b5b556901
Recently I've started to mess around with Android Studio and decided to make an app. I've made the most of my app, but I encounter a little problem. I need to memorize in a variable a number from user input, but I don't know how to that, I've tried solutions found on the internet, even here but I get an error.
Can somebody help me with some ideas or the code edited which I must put in my app ?
This is the java code for the activity:
public class calc_medie_teza extends ActionBarActivity implements View.OnClickListener {
EditText adaug_nota;
static final int READ_BLOCK_SIZE = 100;
TextView afisare;
TextView afisare2;
Button calc;
EditText note_nr;
EditText nota_teza;
int suma;
double medie;
double medieteza;
int nr_note = 0;
int notamedie;
int notateza;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calc_medie_teza);
afisare = (TextView) findViewById(R.id.afisare);
afisare2 = (TextView) findViewById(R.id.afisare2);
calc = (Button) findViewById(R.id.calc);
calc.setOnClickListener(this);
note_nr = (EditText) findViewById(R.id.note_nr);
nota_teza = (EditText) findViewById(R.id.nota_teza);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_calc_medie_teza, menu); // creare meniu
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId(); // meniu
return id == R.id.action_settings || super.onOptionsItemSelected(item);
}
public void onClick(View v) // afisare medie
{
calcul_medie();
}
public void buton_adauga(View v)
{
if(note_nr == )
suma = suma + notamedie;
nr_note = nr_note + 1;
}
public double calcul_medie() // calculul mediei
{
medie = suma / nr_note;
medieteza = ((medie * 3)+ notateza)/4;
return medieteza;
}
Here is a photo with the activity: http://onlypro.ro/img/images/ootllv2f55hnwdgi0xlv.png
Basically the app needs to add the input number to variable when I press the "Adauga nota" [Add grade] button and then I have to insert the "teza" number and when press the "Calculeaza media" [Calculate] the app will then calculate the calcul_medie() and return a decimal number. Between "Introduceti notele aici" [Add grades here] and "Adaugata nota"[Add grade] I have a Number enter text, the same is between "Introduceti teza aici" [Add thesis bere] and "Calculeaza media" [Calculate]. I don't know how to store the number the user puts in and sum it in "notamedie" variable.
I hope you understand my problem.
For any questions you'll have I'll respond as soon as I can.
Thanks in advance !
Well, I think your probably asked how to get the input of the String from the UI and translate them into Integer/BigDecimal. If so, here is some solution:
first, you get get the string from the UI:
String input = note_nr.getText().toString().trim();
change the string input to integer/BigDecimal:
int number1 = Integer.parseInt(input);
BigDecimal number2 = new BigDecimal(input);
Correct me if misunderstood your questions. Thanks.
I did not understand the problem at all. Please clearly define the problem and use english if you can. As fas the I understood there will be a Edittext to which the user will input the value. Gets its value in the activity and then use it.
EditText edittext;
editext = (EditText) findViewById(R.id.editext);
String value = edit text.getText().toString(); // the value that the user inputted in String data format
// Here for addition you will need the value in int or decimal for that
int valueInt = Integer.parse(value); // this will be the value in int type
double valueInt = = Double.parseDouble(value); // this will be the value (user inputted) in double data type ( which you will need if you want to use decimal numbers).
When you press a button just retrieve the appropriate value from the edittext in the following way
edittext = (EditText)layout.findViewById(R.id.txtDescription);
String string = edittext.getText().toString();
to retrieve the text do this
String string = note_nr.getText().toString();
// Converting String to int
int myValue =Integer.parseInt(string);
I tried that one more time, but the IDE says that the variable I used for "string" is never used, but I've used it.
number1= (EditText) findViewById(R.id.number1);
String number_1 = number1.getText().toString();
number2= (EditText) findViewById(R.id.number2);
String number_2= number2.getText().toString();
R3muSGFX, can you post the whole codes?
String number_1 = number1.getText().toString(); this line codes just mean that you initialized a String variable "number_1".
and you will used it when app perform a math function, like you wrote in the beginning:
public double calcul_medie()
{
medie = suma / nr_note;
medieteza = ((medie * 3)+ notateza)/4;
return medieteza;
}
but if you did not use "number_1" at all, IDE will imply you the warning message
:the variable I used for "string" is never used
I have two identical views with a number of editTexts. In one, pre-defined answers are populated in the editTexts (but not shown to the user). In the second, the user starts with all blank editTexts, and then fills them out in an attempt to make them the same as the pre-defined answers.
So I want to loop through the user's view, checking it against the pre-defined one, until an inequality is found, in which case the method will return false.
My code is below. Inside the onCreate I have a buttonListener (when the user is ready to check answers)
btnSolution.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(checkAnswer() == true){
Toast.makeText(getBaseContext(), "all good!", Toast.LENGTH_LONG).show();
}
else {
Toast.makeText(getBaseContext(), "no good", Toast.LENGTH_LONG).show();
}
}
});
the checkAnswer() method is then defined as follows
public boolean checkAnswer() {
final int ROW_COUNT = 15;
final int COL_COUNT = 10;
final String ROWS[] = {"R1","R2","R3","R4","R5","R6","R7","R8","R9","R10","R11","R12","R13","R14","R15"};
final String COLS[] = {"C1","C2","C3","C4","C5","C6","C7","C8","C9","C10"};
for(int i=0; i<ROW_COUNT; i++) {
for(int j=0; j<COL_COUNT; j++) {
String a = ROWS[i];
String b = COLS[j];
int editTextBaseId = getResources().getIdentifier("box" + a + b, "id", getPackageName());
int editTextAnswerId = getResources().getIdentifier("boxA" + a + b, "id", getPackageName());
EditText editTextBase = (EditText)findViewById(editTextBaseId);
EditText editTextAnswer = (EditText)findViewById(editTextAnswerId);
String textBase = editTextBase.getText().toString();
String textAnswer = editTextAnswer.getText().toString();
if(textBase.equals(textAnswer)) {
}
else {
return false;
}
}
}
return true;
}
Unfortunately when I try and run this I am getting a crash and the following error in my LogCat
12-17 00:05:02.075: E/SKIA(16370): FimgApiStretch:stretch failed
Any obvious errors?
That's not an error itself. I guess you're using a Samsung as your target device, if so, don't worry about it.
In the other hand, maybe it's better to compare only the strings. All those findViewById are inneficient.
Looking at your code:
EditText editTextAnswer = (EditText)findViewById(editTextAnswerId);
Do you have both views in the same layout, and the one with the answers is hidden? I mean, if you have the view with blank editTexts as the content of your activity, you can't find the editText with the answer as it's in other xml (assuming you did it as a different xml).