Java GUI Scientific Calculator -

i trying code scientific calculator in java. however, having difficulties trying program calculate. can see in code below, have managed gui working numbers printing on gui. have added functionality "+" button in order test first see if program works.

public class gui extends jframe {     private static jbutton [] button = new jbutton[36];     private static textfield tf;     private jpanel panel;     private jpanel panel1;    public gui(){     super("scientific calculator");     panel = new jpanel();     panel1 = new jpanel(new gridlayout(0,4));      tf = new textfield(20);     tf.seteditable(false);     panel.add(tf);      button[0]=new jbutton("rad/deg");     button[1]=new jbutton("x!");     button[2]=new jbutton("sqrt");     button[3]=new jbutton("sin");     button[4]=new jbutton("cos");     button[5]=new jbutton("tan");     button[6]=new jbutton("ln");     button[7]=new jbutton("log");     button[8]=new jbutton("1/x");     button[9]=new jbutton("e^x");     button[10]=new jbutton("x^2");     button[11]=new jbutton("y^x");     button[12]=new jbutton("|x|");     button[13]=new jbutton("pi");     button[14]=new jbutton("e");      button[15]=new jbutton("c");     button[16]=new jbutton("(");     button[17]=new jbutton(")");     button[18]=new jbutton("%");     button[19]=new jbutton("/");     button[20]=new jbutton("7");     button[21]=new jbutton("8");     button[22]=new jbutton("9");     button[23]=new jbutton("*");     button[24]=new jbutton("4");     button[25]=new jbutton("5");     button[26]=new jbutton("6");     button[27]=new jbutton("-");     button[28]=new jbutton("1");     button[29]=new jbutton("2");     button[30]=new jbutton("3");     button[31]=new jbutton("+");     button[32]=new jbutton(".");     button[33]=new jbutton("0");     button[34] =new jbutton("+/-");     button[35] =new jbutton("=");        for(int = 0; i<button.length;i++){         panel1.add(button[i]);     }       panel.add(panel1);     add(panel);      handlerclass handler = new handlerclass();     for(int = 0; i<button.length;i++){         button[i].addactionlistener(handler);     }  } private class handlerclass implements actionlistener{      @override     public void actionperformed(actionevent e) {         double num1 = 0,num2;          string alreadydisplayed = tf.gettext();         string todisplay = "";          if(e.getsource()==button[33]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[33].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[28]){              alreadydisplayed = tf.gettext();              todisplay = alreadydisplayed + (button[28].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[29]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[29].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[30]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[30].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[24]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[24].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[25]){             alreadydisplayed = tf.gettext();             todisplay = (button[25].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[26]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[26].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[20]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[20].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[21]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[21].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[22]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[22].gettext());             tf.settext(todisplay);         }         if(e.getsource()==button[31]){             alreadydisplayed = tf.gettext();             todisplay = alreadydisplayed + (button[31].gettext());             tf.settext(todisplay);         } 

however problem afterwards. trying have try , catch block see if first input number , convert double, store in array can use operator function afterwards , keep adding numbers until user wants stop , perform calculation. attempt @ code below, wrong. can please suggest doing wrong? thanks

try{     num1 = double.parsedouble(todisplay); } catch(numberformatexception e1){     system.out.println("you have not entered number"); } double[] arr = new double[10]; for(int i=0; i<arr.length;i++){     arr[i]=num1;     string test = string.valueof(arr[i]);     tf.settext(test); } 

edit have wrote new code simple calculator recommended user , works 2 inputs. still getting errors when try implement multiple inputs. below working code 2 input calculator.

import javax.swing.*;  import java.awt.*; import java.awt.event.*;  public class calcgui extends jframe {      private jbutton buttonzero;     private jbutton buttonone;     private jbutton buttontwo;     private jbutton buttonthree;     private jbutton buttonfour;     private jbutton buttonfive;     private jbutton buttonsix;     private jbutton buttonseven;     private jbutton buttoneight;     private jbutton buttonnine;      private jbutton opbuttonplus;     private jbutton opbuttonminus;     private jbutton opbuttondivide;     private jbutton opbuttonmultiply;     private jbutton opbuttonequals;     private jbutton opbuttonclear;      private textfield tf;      private jpanel numbuttonpanel;     private jpanel opbuttonpanel;     private jpanel basepanel;      public calcgui(){         super("scientific calculator");         basepanel = new jpanel();         numbuttonpanel = new jpanel(new gridlayout(0,4));         opbuttonpanel = new jpanel(new gridlayout(0,1));          tf = new textfield(20);         tf.seteditable(false);         basepanel.add(tf);           buttonzero = new jbutton("0");          numbuttonpanel.add(buttonzero);          buttonone = new jbutton("1");          numbuttonpanel.add(buttonone);          buttontwo = new jbutton("2");          numbuttonpanel.add(buttontwo);          buttonthree = new jbutton("3");          numbuttonpanel.add(buttonthree);          buttonfour = new jbutton("4");          numbuttonpanel.add(buttonfour);          buttonfive = new jbutton("5");          numbuttonpanel.add(buttonfive);          buttonsix = new jbutton("6");          numbuttonpanel.add(buttonsix);          buttonseven = new jbutton("7");          numbuttonpanel.add(buttonseven);          buttoneight = new jbutton("8");          numbuttonpanel.add(buttoneight);          buttonnine = new jbutton("9");          numbuttonpanel.add(buttonnine);           basepanel.add(numbuttonpanel);          opbuttonplus = new jbutton("+");         opbuttonminus = new jbutton("-");         opbuttondivide = new jbutton("/");         opbuttonmultiply = new jbutton("*");         opbuttonequals = new jbutton("=");         opbuttonclear = new jbutton("c");          opbuttonpanel.add(opbuttonplus);         opbuttonpanel.add(opbuttonminus);         opbuttonpanel.add(opbuttondivide);         opbuttonpanel.add(opbuttonmultiply);         opbuttonpanel.add(opbuttonequals);         opbuttonpanel.add(opbuttonclear);          basepanel.add(opbuttonpanel);          add(basepanel);          handlerclass handler = new handlerclass();          buttonzero.addactionlistener(handler);         buttonone.addactionlistener(handler);         buttontwo.addactionlistener(handler);         buttonthree.addactionlistener(handler);         buttonfour.addactionlistener(handler);         buttonfive.addactionlistener(handler);         buttonsix.addactionlistener(handler);         buttonseven.addactionlistener(handler);         buttoneight.addactionlistener(handler);         buttonnine.addactionlistener(handler);          opbuttonplus.addactionlistener(handler);         opbuttonminus.addactionlistener(handler);         opbuttondivide.addactionlistener(handler);         opbuttonmultiply.addactionlistener(handler);         opbuttonequals.addactionlistener(handler);         opbuttonclear.addactionlistener(handler);      }       private class handlerclass implements actionlistener{         public void actionperformed(actionevent e){             string alreadydisplayed = tf.gettext();             if(e.getsource()==buttonzero){                 string buttonzerotext = alreadydisplayed + buttonzero.gettext();                 tf.settext(buttonzerotext);             }else if(e.getsource()==buttonone){                 string buttononetext = alreadydisplayed + buttonone.gettext();                 tf.settext(buttononetext);             }else if(e.getsource()==buttontwo){                 string buttontwotext = alreadydisplayed + buttontwo.gettext();                 tf.settext(buttontwotext);             }else if(e.getsource()==buttonthree){                 string buttonthreetext = alreadydisplayed + buttonthree.gettext();                 tf.settext(buttonthreetext);             }else if(e.getsource()==buttonfour){                 string buttonfourtext = alreadydisplayed + buttonfour.gettext();                 tf.settext(buttonfourtext);             }else if(e.getsource()==buttonfive){                 string buttonfivetext = alreadydisplayed + buttonfive.gettext();                 tf.settext(buttonfivetext);             }else if(e.getsource()==buttonsix){                 string buttonsixtext = alreadydisplayed + buttonsix.gettext();                 tf.settext(buttonsixtext);             }else if(e.getsource()==buttonseven){                 string buttonseventext = alreadydisplayed + buttonseven.gettext();                 tf.settext(buttonseventext);             }else if(e.getsource()==buttoneight){                 string buttoneighttext = alreadydisplayed + buttoneight.gettext();                 tf.settext(buttoneighttext);             }else if(e.getsource()==buttonnine){                 string buttonninetext = alreadydisplayed + buttonnine.gettext();                 tf.settext(buttonninetext);             }else if(e.getsource()==opbuttonplus){                 string opbuttonplustext = alreadydisplayed + opbuttonplus.gettext();                 tf.settext(opbuttonplustext);             }else if(e.getsource()==opbuttonequals){                 string opbuttonequalstext = alreadydisplayed + opbuttonequals.gettext();                 tf.settext(opbuttonequalstext);             }else if(e.getsource()==opbuttonminus){                 string opbuttonminustext = alreadydisplayed + opbuttonminus.gettext();                 tf.settext(opbuttonminustext);             }else if(e.getsource()==opbuttonmultiply){                 string opbuttonmultiplytext = alreadydisplayed + opbuttonmultiply.gettext();                 tf.settext(opbuttonmultiplytext);             }else if(e.getsource()==opbuttondivide){                 string opbuttondividetext = alreadydisplayed + opbuttondivide.gettext();                 tf.settext(opbuttondividetext);             }else if(e.getsource()==opbuttonclear){                 string opbuttoncleartext = "";                 tf.settext(opbuttoncleartext);             }               double result;             for(int i=0; i<alreadydisplayed.length();i++){                  if(e.getsource()==opbuttonequals){                      if(alreadydisplayed.charat(i)=='+'){                         result = double.parsedouble(alreadydisplayed.substring(0,i)) + double.parsedouble(alreadydisplayed.substring(i+1,alreadydisplayed.length()));                         tf.settext(alreadydisplayed + "=" + result);                     }else if(alreadydisplayed.charat(i)=='-'){                         result = double.parsedouble(alreadydisplayed.substring(0,i)) - double.parsedouble(alreadydisplayed.substring(i+1,alreadydisplayed.length()));                         tf.settext(alreadydisplayed + "=" + result);                     }else if(alreadydisplayed.charat(i)=='/'){                         result = double.parsedouble(alreadydisplayed.substring(0,i)) / double.parsedouble(alreadydisplayed.substring(i+1,alreadydisplayed.length()));                         tf.settext(alreadydisplayed + "=" + result);                     }else if(alreadydisplayed.charat(i)=='*'){                         result = double.parsedouble(alreadydisplayed.substring(0,i)) * double.parsedouble(alreadydisplayed.substring(i+1,alreadydisplayed.length()));                         tf.settext(alreadydisplayed + "=" + result);                     }                 }             }         }     } } 

the part having difficulties getting number , storing can let user enter more 2 values. example if take out loop @ end of above code , replaced this;

double []num1=new double[10];     double []num2=new double[10];     //double num1 = 0;     double temp =0;     string str[] = new string [10];     string []str1 = new string[10];     if(e.getactioncommand().equals("+"))     if(e.getsource() == opbuttonequals)         for( int = 0; i<alreadydisplayed.length(); i++){              if(alreadydisplayed.charat(i)=='+')              str[i] = alreadydisplayed.substring(0,i);              num1[i] = double.parsedouble(str[i]);              str1[i+1] = alreadydisplayed.substring(i+1,alreadydisplayed.length());              num2[i+1] = double.parsedouble(str1[i]);               temp += num1[i] + num2[i+1];              tf.settext(double.tostring(temp));          }system.out.println(temp);     } } 

so when try test see if temp has value in console, prints 0 out each time. string text showing in text field, there no actual calculation working. thought work storing number , storing number , adding them has not.

why not store values string (much easier manipulate), , parse arithmetic expression later? example..

person presses buttons "(", "sin(8)", "+", "8", ")", "+", "1", "="

that evaluates easy string of (sin(8)+8)+1=

you can parse string , obvious things need parsed (e.g. sin, parse between brackets recursively). use math functions evaluate complex expressions, , parse simple ones.

i might recommend writing own functions solve complex expressions though - similar this...

public double solvesin(string inside) {   if(numberutils.isnumber(inside)) {     return math.sin(double.parsedouble(inside);   } else {     //call original function direct based on inputs     return math.sin(parseequation(inside));   } }