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Thread: Calculator double zero button issue.

  1. #1
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    Default Calculator double zero button issue.

    hi members I am beginner in android development Here some issue in calculator with my Double zero button for example when i press btn 1 for one and btn 00 for double zero and again press btn 1 for one so my result should be 1001. but my calculator write 1010. it write the last 1 between the two zero. Please anyone help me.

    my code is below

    public void btndoublezero(View view) {
    updateText("00");
    }

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Calculator double zero button issue.

    Can you post the code that is the problem?
    Be sure to wrap in code tags.

    If "00" is converted to a numeric value, it will print as 0.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following User Says Thank You to Norm For This Useful Post:

    mtahirkn (April 26th, 2021)

  4. #3
    Super Moderator Norm's Avatar
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    Default Re: Calculator double zero button issue.

    Please edit your post and wrap your code with code tags:

    [code]
    **YOUR CODE GOES HERE**
    [/code]

    to get highlighting and preserve formatting.

    How are you trying to debug the code? To see what happens add some print statements that print out the values in the variables. The print out will be in the logcat.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #4
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    Default Re: Calculator double zero button issue.

     
    package com.example.englishcalculator;
     
    import androidx.annotation.RequiresApi;
    import androidx.appcompat.app.AppCompatActivity;
    import org.mariuszgromada.math.mxparser.*;
    import android.os.Build;
    import android.os.Bundle;
    import android.text.SpannableStringBuilder;
    import android.view.Display;
    import android.view.View;
    import android.widget.EditText;
    import android.widget.ImageView;
     
    public class MainActivity extends AppCompatActivity {
     
        private EditText display;
     
     
        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
     
            display = findViewById(R.id.input);
            display.setShowSoftInputOnFocus(false);
            display.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                 if (getString(R.string.display).equals(display.getText().toString())){
                     display.setText("");
                 }
                }
            });
        }
        private void updateText(String strToAdd){
            String OldStr = display.getText().toString();
            int cursorPos = display.getSelectionStart();
            String leftStr = OldStr.substring(0, cursorPos);
            String rightStr = OldStr.substring(cursorPos);
            if (getString(R.string.display).equals(display.getText().toString())){
                display.setText(strToAdd);
                display.setSelection(cursorPos + 1);
            }
            else {display.setText(String.format("%s%s%s", leftStr, strToAdd, rightStr));
                display.setSelection(cursorPos + 1);
     
            }
        }
     
        public void btnzero(View view) {
            updateText("0");
        }
     
        public void btnone(View view) {
            updateText("1");
     
        }
     
        public void btntwo(View view)
        { updateText("2");
        }
     
        public void btnthree(View view) {
            updateText("3");
        }
     
        public void btnfour(View view) {
            updateText("4");
     
        }
     
        public void btnfive(View view) {
            updateText("5");
        }
     
        public void btnsix(View view) {
            updateText("6");
        }
     
        public void btnseven(View view) {
            updateText("7");
        }
     
        public void btneight(View view) {
            updateText("8");
        }
     
        public void btnnine(View view) {
            updateText("9");
        }
     
     
        public void btnclear(View view){
            display.setText("0");
            }
     
     
        public void btnparenteses(View view) {
            int cursorPos = display.getSelectionStart();
            int openPar = 0;
            int closedPar = 0;
            int textLen = display.getText().length();
            for (int i = 0; i < cursorPos; i++){
            if ( display.getText().toString().substring(i, i+1) .equals("(")){
                openPar += 1;
            }
                if ( display.getText().toString().substring(i, i+1) .equals(")")){
                    closedPar += 1;
                }
            }
                if (openPar == closedPar || display.getText().toString().substring(textLen-1, textLen).equals("(")){
                     updateText("(");
     
                }
               else if (closedPar < openPar && !display.getText().toString().substring(textLen-1, textLen).equals(")")){
                updateText(")");
     
            }
            display.setSelection(cursorPos + 1);
        }
     
        public void btndevide(View view) {
            updateText("");
        }
     
        public void btnmultiply(View view) {
            updateText("");
        }
     
        public void btnsubtract(View view) {
            updateText("-");
        }
     
        public void btnadd(View view) {
            updateText("+");
        }
     
        public void btndoublezero(View view) {
            updateText("00");
        }
     
        public void btnpoint(View view) {
            updateText(".");
        }
     
        public void btnexponent(View view) {
            updateText("^");
        }
     
     
        public void btnequal(View view) {
        String userExp = display.getText().toString();
     
        userExp = userExp.replaceAll("", "/");
        userExp = userExp.replaceAll("", "*");
        Expression exp = new Expression(userExp);
        String result = String.valueOf(exp.calculate());
        display.setText(result);
        display.setSelection(result.length());
     
        }
        public void btnbackspace(View view) {
     
            int cursorPos = display.getSelectionStart();
            int textLen = display.getText().length();
            if (cursorPos != 0 && textLen !=0) {
                SpannableStringBuilder selection = (SpannableStringBuilder) display.getText();
                selection.replace(cursorPos -1, cursorPos, "" );
                display.setText(selection);
                display.setSelection(cursorPos - 1);
            }
        }
    }

  6. #5
    Super Moderator Norm's Avatar
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    Default Re: Calculator double zero button issue.

    I don't see any print statements in the updateText method for debugging.
    You need to debug the code to see why it is doing what it is doing. Add some print statements to show the values of all the variables used in the updateText method. The print out in the logcat will show you what the code is doing when it executes.

    Please add some comments to the code in the updateText method that explain what it is trying to do.
    For example:
    what is leftStr and rightStr about?
    What is the use of the cursorPos variable?
    Why is cursorPos updated by 1?
    If you don't understand my answer, don't ignore it, ask a question.

  7. #6
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    Default Re: Calculator double zero button issue.

    Now I solve the issue. here is the code I add.

    public void btndoublezero(View view) {
            updateText("00");
            EditText editText = (EditText)findViewById(R.id.input);
            editText.setSelection(editText.getText().length());
        }

  8. #7
    Super Moderator Norm's Avatar
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    Default Re: Calculator double zero button issue.

    The new code considers that double zero has 2 characters and all the others only 1 character.
    If you don't understand my answer, don't ignore it, ask a question.

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