android - simple calculator on Android

Hello.

I study the development under android, I write banal tasks (now – calculator).
And here’s actually a question – I shaped a string with an expression, how can I count it now? If I had a complex calculator, I would use the methods of reverse Polish record and other already known algorithms. But I have +, -, *, /. In the scripting languages, I would use something like eval (), and here it turned around …

Help, if you encountered, please:)

Answer 1, Authority 100%

main.xml

& lt; xml version = "1.0" encoding = "UTF-8"? & gt;
& lt; linearlayout XMLNS: Android = "http://schemas.android.com/apk/res/android"
  Android: layout_width = "fill_parent"
  Android: layout_height = "fill_parent"
  Android: Orientation = "Vertical" & gt;
  & lt; editText
    Android: id = "@ + id / edittext1"
    Android: layout_width = "fill_parent"
    Android: layout_height = "wrap_content"
    Android: InputType = "Number" & gt;
    & lt; RequestFocus / & GT;
  & lt; / edittext & gt;
& lt; tableow
  Android: layout_width = "wrap_content"
  Android: layout_height = "wrap_content" & gt;
  & lt; button
    Android: id = "@ + id / button1"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Layout_Gravity = "Center"
    Android: text = "1" / & gt;
  & lt; button
    Android: id = "@ + id / button2"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "2" / & gt;
  & lt; button
    Android: id = "@ + id / button3"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "3" / & gt;
  & lt; button
    Android: id = "@ + id / button4"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "+" / & gt;
  & lt; button
    Android: id = "@ + id / button5"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "-" / & gt;
& lt; / tablerow & gt;
  & lt; tableow
  Android: layout_width = "wrap_content"
  Android: layout_height = "wrap_content" & gt;
  & lt; button
    Android: id = "@ + id / button6"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Layout_Gravity = "Center"
    Android: Text = "4" / & gt;
  & lt; button
    Android: id = "@ + id / button7"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "5" / & gt;
  & lt; button
    Android: id = "@ + id / button8"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "6" / & gt;
  & lt; button
    Android: id = "@ + id / button9"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "/" / & gt;
  & lt; button
    Android: id = "@ + id / button10"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "*" / & gt;
& lt; / tablerow & gt;
  & lt; tableow
  Android: layout_width = "wrap_content"
  Android: layout_height = "wrap_content" & gt;
  & lt; button
    Android: id = "@ + id / button11"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Layout_Gravity = "Center"
    Android: Text = "7" / & gt;
  & lt; button
    Android: id = "@ + id / button12"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "8" / & gt;
  & lt; button
    Android: id = "@ + id / button13"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "9" / & gt;
  & lt; button
    Android: id = "@ + id / button20"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "0" / & gt;
  & lt; button
    Android: id = "@ + id / button14"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "=" / & gt; 
& lt; / tablerow & gt;
 & lt; tableow
  Android: layout_width = "wrap_content"
  Android: layout_height = "wrap_content" & gt;
  & lt; button
    Android: id = "@ + id / beutton16"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: text = "Decimal" / & gt;
  & lt; button
    Android: id = "@ + id / button23"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "Binary" / & gt;
  & lt; button
    Android: id = "@ + id / button22"
    Android: layout_width = "fill_parent"
    Android: layout_height = "fill_parent"
    Android: Text = "Clear" / & gt;
& lt; / tablerow & gt;
& lt; / linearlayout & gt;

activity.java

package calc.calc;
Import java.util.arraylist;
Import Android.app.ActiveIVITY;
Import android.os.Bundle;
Import android.text.method.digitsKeylistener;
Import Android.View.View;
Import android.widget.EditText;
Import android.widget.textView;
Public Class Calcactivity EXTENDS ACTIVITY {
  / ** textball variable * /
  EditText CalcdialogDisplay;
  / ** variable buttons * /
  TextView Binary;
  TextView AllClear;
  TextView Seven;
  TextView EIGHT;
  TextView Nine;
  TextView Division;
  TextView Four;
  TextView Five;
  TextView Six;
  TextView Multiply;
  TextView One;
  TextView Two;
  TextView Three;
  TextView subtract;
  TextView Decimal;
  TextView Zero;
  TextView Equals;
  TextView Addition;
  / ** The result that is entered into module for processing * /
  ArrayList & lt; Float & gt; Result = New ArrayList & LT; Float & gt; ();
  / ** first entered number * /
  Float Number1;
  / ** Second entered number * /
  Float Number2;
  int currentoperation = 0;
  INT NEXTOPERATION;
  /**Addition*/
  Final Static int Add = 1;
  /**Subtraction*/
  Final Static Int SUBTRACT = 2;
  /**Multiplication*/
  Final Static Int Multiply = 3;
  /**Division*/
  Final Static Int Division = 4;
  /**Equals*/
  Final Static In Equals = 5;
  / ** Finding an integer value from binary number * /
  Final Static Int Decimal = 6;
  / ** Finding a binary number from the whole * /
  Final Static Int Binary = 7;
  Final Static int Clear = 1;
  Final Static Int Dont_Clear = 0;
  int ClearCalcDisplay = 0;
  Public Void OnCreate (Bundle SavedInstanceState) {
    Super.ONCREATE (SavedInstanceState);
    setContentView (R.Layout.main);
    calcdialogdisplay = (editText) FindViewByid (R.ID.EditText1);
    binary = (textView) FindViewByid (R.ID.Button23);
    Allclear = (TextView) FindViewByid (R.ID.Button22);
    Seven = (textView) FindViewByID (R.ID.Button11);
    EIGHT = (TextView) FindViewByid (R.ID.Button12);
    Nine = (TextView) FindViewByid (R.ID.Button13);
    Division = (TextView) FindViewByid (R.ID.Button9);
    Four = (TextView) FindViewByid (R.ID.Button6);
    Five = (TextView) FindViewByid (R.ID.Button7);
    Six = (TextView) FindViewByid (R.ID.Button8);
    Multiply = (TextView) FindViewByID (R.ID.Button10);
    One = (TextView) FindViewByID (R.ID.Button1);
    Two = (TextView) FindViewByid (R.ID.Button2);
    Three = (TextView) FindViewByid (R.ID.Button3);
    subtract = (TextView) FindViewByid (R.ID.Button5);
    Decimal = (TextView) FindViewByid (R.ID.Button16);
    zero = (textView) FindViewByid (R.ID.Button20);
    Equals = (TextView) FindViewByid (R.ID.Button14);
    // addition = (TextView) FindViewByid (R.ID.Addition);
    calcdialogdisplay.setkeylistener (DigitsKeylistener.getInstance (True, True));
    registerlisteners ();
  }
  / * Handling on the screen * /
  Public void registerlisteners () {
    Seven.SetonClicklistener (new view.onclicklistener () {
      @Override
      Public Void OnClick (View V) {
        If (ClearCalcDisplay == Clear) {
          calcdialogdisplay.settext ("");
        }
        ClearCalcDisplay = dont_Clear;
        calcdialogdisplay.append ("7");
      }
    });
    Eight.SetonClicklistener (new view.onclicklistener () { 
@Override
      Public Void OnClick (View V) {
        If (ClearCalcDisplay == Clear) {
          calcdialogdisplay.settext ("");
        }
        ClearCalcDisplay = dont_Clear;
        calcdialogdisplay.append ("8");
      }
    });
    Nine.SetonClicklistener (new view.onclicklistener () {
      @Override
      Public Void OnClick (View V) {
        If (ClearCalcDisplay == Clear) {
          calcdialogdisplay.settext ("");
        }
        ClearCalcDisplay = dont_Clear;
        calcdialogdisplay.append (9 ");
      }
    });
    Division.SetonClicklistener (new view.onclicklistener () {
      @Override
      Public Void OnClick (View V) {
        CalClogic (Division);
      }
    });
    Allclear.SetonClicklistener (new view.onclicklistener () {
      @Override
      Public Void OnClick (View V) {
        calcdialogdisplay.settext ("");
        NUMBER1 = 0;
        NUMBER2 = 0;
        Result.Removeall (Result);
        currentoperation = 0;
        NEXTOPERATION = 0;
      }
    });
  Four.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("4");
    }
  });
  Five.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("5");
    }
  });
  Six.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("6");
    }
  });
  Zero.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("0");
    }
  });
  Decimal.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      CalClogic (Decimal);
    }
  });
  Multiply.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      CalClogic (Multiply);
    }
  });
  One.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("1");
    }
  });
  Two.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("2");
    }
  });
  Three.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      If (ClearCalcDisplay == Clear) {
        calcdialogdisplay.settext ("");
      }
      ClearCalcDisplay = dont_Clear;
      calcdialogdisplay.append ("3");
    }
  });
  subtract.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) {
      CalClogic (subtract);
    }
  });
  Equals.SetonClicklistener (new view.onclicklistener () {
    @Override
    Public Void OnClick (View V) { 
calcLogic (EQUALS);
    }
  });
  binary.setOnClickListener (new View.OnClickListener () {
    @Override
    public void onClick (View v) {
      calcLogic (BINARY);
    }
  });
}
  / * Function for converting from decimal to binary * /
  private float decToBin (float bin) {
    int i, b;
    long result = 0;
     for (i = 0; bin & gt; 0; i ++) {
      b = (int) (bin% 2);
      bin = (bin-b) / 2;
      result + = b * Math.pow (10, i);
    }
     return result;
  }
  / * Conversion function from two-faced to decimal value * /
  private float binToDec (float dec) {
    int result = 0;
    int mult = 1;
    while (dec & gt; 0) {
      result + = mult * ((int) dec% 10);
      dec / = 10;
      mult * = 2;
    }
    return result;
  }
  / * Function for calculating entered values * /
  private void calcLogic (int operator) {
  result.add (Float.parseFloat (calcDialogDisplay.getText (). toString ()));
  if (operator! = EQUALS) {
    nextOperation = operator;
  } else if (operator == EQUALS) {
    nextOperation = 0;
  }
  switch (currentOperation) {
  /*Addition*/
    case ADD:
      number1 = result.get (0);
      number2 = result.get (1);
      result.removeAll (result);
      result.add (number1 + number2);
      calcDialogDisplay.setText (String.format ("%. 0f", result.get (0)));
      break;
   /*Subtraction*/
    case SUBTRACT:
      number1 = result.get (0);
      number2 = result.get (1);
      result.removeAll (result);
      result.add (number1 - number2);
      calcDialogDisplay.setText (String.format ("%. 0f", result.get (0)));
      break;
   /*Multiplication*/
    case MULTIPLY:
      number1 = result.get (0);
      number2 = result.get (1);
      result.removeAll (result);
      result.add (number1 * number2);
      calcDialogDisplay.setText (String.format ("%. 0f", result.get (0)));
      break;
    /*Division*/
    case DIVISION:
      number1 = result.get (0);
      number2 = result.get (1);
      result.removeAll (result);
      result.add (number1 / number2);
      calcDialogDisplay.setText (String.format ("%. 0f", result.get (0)));
      break;
    / * Get binary number * /
    case DECIMAL:
       number2 = result.get (1);
       result.removeAll (result);
       result.add (decToBin (number2));
       calcDialogDisplay.setText (String.format ("%. 0f", result.get (0)));
      break;
    / * Get decimal number * /
    case BINARY:
       number2 = result.get (1);
       result.removeAll (result);
       result.add (binToDec (number2));
       calcDialogDisplay.setText (String.format ("%. 0f", result.get (0)));
      break;
  }
  clearCalcDisplay = CLEAR;
  currentOperation = nextOperation;
  if (operator == EQUALS) {
    number1 = 0;
    number2 = 0;
    result.removeAll (result);
  }
}
}

Once upon a time failed for an interview

Answer 2

Parse the string and add the numbers, if the number is followed by space (s), or “+”, “-” if spaces and “*”, “/” then perform the action first and look further (recursion), if then the number then fold, if not repeat.

simple calculator on Android

Answer 1, Authority 100%

Answer 2

Programmers, Start Your Engines!

Recent questions

yandex cards disappear labels with zoom

Embarcadero C++ Builder 10.3 does not give prompts by code

Found input variables with inconsistent numbers of samples error

Return to previous page

Lua C++ error handling