java - Multiplication in Calculator Android App throwing alphabeta in output -


below code calculator android app making:

package com.example.calculator;  import java.text.decimalformat; import java.text.numberformat; import java.util.iterator; import java.util.stack; import java.lang.math;  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 activity 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 stack         minputstack = new stack<string>();         moperationstack = new stack<string>();          // reference keypad button gridview         mkeypadgrid = (gridview) findviewbyid(r.id.grdbuttons);          // reference 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 keypad grid         mkeypadgrid.setadapter(mkeypadadapter);          // set button click listener of keypad adapter         mkeypadadapter.setonbuttonclicklistener(new onclicklistener() {             @override             public void onclick(view v) {                 button btn = (button) v;                 // keypadbutton value used identify                 // keypad button 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 1 character @ input reset input 0             if (endindex < 1) {                 userinputtext.settext("0");             }             // trim last character of input text             else {                 userinputtext.settext(currentinput.subsequence(0, endindex));             }             break;         case sign: // handle -/+ sign             // input has text , different initial value 0             if (currentinputlen > 0 && currentinput != "0") {                 // has (-) sign. remove 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 , stack             userinputtext.settext("0");             clearstacks();             break;         case decimal_sep: // handle decimal separator             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 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 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 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 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> = 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));         }     }  } 

when give inputs 45454545454545 * 54545454545454, output shown 2.479338842975157e27. alphabet e in output.

the multiplication code is:

  if (operator.equals(keypadbutton.multiply.gettext())) {             result = leftval * rightval;   } 

instead of e, want show result _______ * 10^x. can me how fix this? in advance.

you're talking how display numbers.. can use numberformat specify how number should displayed, e.g.:

numberformat formatter = new decimalformat("#0.00"); 

for more info:

  1. http://developer.android.com/reference/java/text/numberformat.html
  2. http://developer.android.com/reference/java/text/decimalformat.html

here example: http://www.coderzheaven.com/2012/10/14/numberformat-class-android-rounding-number-android-formatting-decimal-values-android/

if want keep , want replace exponential e ^, why not try:

string.replace("e", "^")  

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