Calculator Problems - Android Programming

Question

I'm trying to design a simple calculator for use as a scoreboard for a game or two. Ultimately, I want to be able to select the number of players, have that many score-trackers appear on screen, be able to use a the touch calculator to add or subtract (or divide or multiply) I got it to work for the most part.

Currently, it takes the text inputted in the calculator display, adds/subtracts/whatever that to the player score that I choose.

The problem is trying to get the numerical keys to show up in the calculator display part. For instance, I want to be able to hit "1" then "0" and have "10" appear in the calculator. It should have been easy, seeing as I am able to input text MANUALLY (using the android default keyboard), but the closest I can get is for only 1 number to show up at a time...

Long story short, I am trying to get a touch-pad type calculator's numerical buttons to work and display. Below is my main project code. If you need my layout code, I can post that as well (for references to IDs).

I know it's probably a simple solution, but every tutorial I find is either overly complicated or does not work... ANY help is greatly appreciated!

package com.MCalculator8.test;

import com.MCalculator8.test.R;

import android.app.Activity;
import android.app.AlertDialog;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MCalculator8Activity extends Activity {
    private EditText player1name;
    private EditText player2name;
    private EditText player3name;
    private EditText player4name;
    private EditText player5name;
    private EditText player6name;
    private EditText player7name;

    private EditText player1score;
    private EditText player2score;
    private EditText player3score;
    private EditText player4score;
    private EditText player5score;
    private EditText player6score;
    private EditText player7score;

    private EditText input;

    private TextView operator;
    private MCalculator8Activity mContext;

    // Called when the activity is first created. 
    @Override
    public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            mContext = this;

            setContentView(R.layout.main);

            player1name = (EditText) findViewById(R.id.player1name);
            player2name = (EditText) findViewById(R.id.player2name);
            player3name = (EditText) findViewById(R.id.player3name);
            player4name = (EditText) findViewById(R.id.player4name);
            player5name = (EditText) findViewById(R.id.player5name);
            player6name = (EditText) findViewById(R.id.player6name);
            player7name = (EditText) findViewById(R.id.player7name);

            input = (EditText) findViewById(R.id.input);

            player1score = (EditText) findViewById(R.id.player1score);
            player2score = (EditText) findViewById(R.id.player2score);
            player3score = (EditText) findViewById(R.id.player3score);
            player4score = (EditText) findViewById(R.id.player4score);
            player5score = (EditText) findViewById(R.id.player5score);
            player6score = (EditText) findViewById(R.id.player6score);
            player7score = (EditText) findViewById(R.id.player7score);

            operator = (TextView) findViewById(R.id.operator);

            // We create an OnClick Event in each button.

            Button plusButton = (Button) findViewById(R.id.add);
            Button minusButton = (Button) findViewById(R.id.subtract);
            Button multiplyButton = (Button) findViewById(R.id.multiply);
            Button player1equals = (Button) findViewById(R.id.player1equals);
            Button player2equals = (Button) findViewById(R.id.player2equals);
            Button player3equals = (Button) findViewById(R.id.player3equals);
            Button player4equals = (Button) findViewById(R.id.player4equals);
            Button player5equals = (Button) findViewById(R.id.player5equals);
            Button player6equals = (Button) findViewById(R.id.player6equals);
            Button player7equals = (Button) findViewById(R.id.player7equals);

            plusButton.setOnClickListener(new OnClickListener() {

                    public void onClick(View arg0) {

                            operator.setText("+");

                    }

            });

            minusButton.setOnClickListener(new OnClickListener() {

                    public void onClick(View arg0) {

                            operator.setText("-");

                    }

            });

            multiplyButton.setOnClickListener(new OnClickListener() {

                    public void onClick(View arg0) {

                            operator.setText("x");

                    }

            });


            player1equals.setOnClickListener(new OnClickListener() {

                    private AlertDialog show;

                    public void onClick(View arg0) {

                            if ((input.getText().length() == 0)
                                            || (input.getText().toString() == " ")) {
                                         //   || (input2.getText().length() == 0)
                                         //   || (input2.getText().toString() == " ")) {

                                    show = new AlertDialog.Builder(mContext).setTitle("Error")
                                                    .setMessage("Some inputs are empty")
                                                    .setPositiveButton("OK", null).show();

                            } else if (operator.getText().equals("")) {

                                    show = new AlertDialog.Builder(mContext).setTitle("Error")
                                                    .setMessage("Operator is null").setPositiveButton(
                                                                    "OK", null).show();

                            } else if (operator.getText().equals("+")) {

                                    double result = new Double(input.getText().toString())
                                                    + new Double(player1score.getText().toString());

                                    player1score.setText(Double.toString(result));

                            } else if (operator.getText().equals("-")) {

                                    double result = new Double(player1score.getText().toString())
                                                    - new Double(input.getText().toString());

                                    player1score.setText(Double.toString(result));

                            } else if (operator.getText().equals("x")) {

                                    double result = new Double(input.getText().toString())
                                                    * new Double(player1score.getText().toString());


                                    player1score.setText(Double.toString(result));

                            }

                    }

            });

score 1 · Answer 1 · answered Feb 24 '12 at 17:17

1

Couldn't you have a String that you could append to every time a button on the calculator is pressed? Then update the calculator display with the new String?

answered Feb 24 '12 at 17:17

Jon

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That's what's confusing me. I tried to get that to work, but I MUST be doing something wrong. I don't understand 100% of the coding yet... – user1231255 Feb 24 '12 at 18:46

score 1 · Accepted Answer · answered Feb 24 '12 at 22:34

How is this example?

Here is the Main Class called "CalculatorExample.java"

package com.calculatorExample;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class CalculatorExample extends Activity implements android.view.View.OnClickListener{
    Button add, subtract, multiply, divide;
    TextView firstInput, secondInput, output;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Reference TextViews and Buttons
        firstInput = (TextView) findViewById(R.id.firstIput);
        secondInput = (TextView) findViewById(R.id.secondInput);
        output = (TextView) findViewById(R.id.output);
        add = (Button) findViewById(R.id.add);
        subtract = (Button) findViewById(R.id.subtract);
        multiply = (Button) findViewById(R.id.multiply);
        divide = (Button) findViewById(R.id.divide);

        // Set listeners for when buttons are pressed
        add.setOnClickListener(this);
        subtract.setOnClickListener(this);
        multiply.setOnClickListener(this);
        divide.setOnClickListener(this);

    }

    /**
     * Switch statement to decide which button was pressed
     */
    public void onClick(View arg0) {
        // Get values from top two TextViews
        double firstInputValue = Double.parseDouble(firstInput.getText().toString());
        double secondInputValue = Double.parseDouble(secondInput.getText().toString());
        // Initialise output
        double outputValue = 0;

        // Perform relevant operations
        switch(arg0.getId()){
        case R.id.add:
            outputValue = firstInputValue + secondInputValue;
            break;
        case R.id.subtract:
            outputValue = firstInputValue - secondInputValue;
            break;
        case R.id.multiply:
            outputValue = firstInputValue * secondInputValue;
            break;
        case R.id.divide:
            outputValue = firstInputValue / secondInputValue;
            break;
        }
        // Add result to Running total stored in output TextView
        outputValue += Double.parseDouble(output.getText().toString());
        output.setText("" + outputValue);

    }
}

And here is the XML file ("main.xml")

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <LinearLayout 
        android:weightSum="100"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
    >
        <EditText 
            android:layout_weight="50"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/firstIput">
        </EditText>
        <EditText 
            android:layout_weight="50"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" 
            android:id="@+id/secondInput">
        </EditText>
    </LinearLayout>
    <LinearLayout 
        android:weightSum="100"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
    >
        <Button 
            android:layout_weight="50"
            android:text="+" 
            android:id="@+id/add" 
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">
        </Button>
        <Button 
            android:layout_weight="50"
            android:text="-" 
            android:id="@+id/subtract" 
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">
        </Button>
    </LinearLayout>
    <LinearLayout 
        android:weightSum="100"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
    >
        <Button 
            android:layout_weight="50"
            android:text="X" 
            android:id="@+id/multiply" 
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">
        </Button>
        <Button 
            android:layout_weight="50"
            android:text="/" 
            android:id="@+id/divide"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">
        </Button>
    </LinearLayout>
    <EditText 
        android:text="0.0"
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:id="@+id/output">
    </EditText>
</LinearLayout>

Thanks for the quick demo! I all ready have the calculator part of this working though, I'm concerned about the "touchpad" part of a calculator. More specifically how to append a textedit (or textview) field with the numbers pressed. For example, pressing the "1" button, then the "2" button (on screen) results in the textedit field displaying "12". It sounds so simple, but I just cannot get it to work. I'm going to mess with it some today and will post if I can get it working. In the mean time, any tips are appreciated!! — user1231255, Feb 27 '12 at 15:10
Well that demo shows how to do that. outputValue += Double.parseDouble(output.getText().toString()); That code gets what is currently in the editText and the line below it adds to that. — Jon, Feb 27 '12 at 21:06
Yes, but it adds to it, it doesnt append the field. If I add both string Doubles, it literally adds the numbers and outputs the sum, rather than adding the number AFTER the existing number. I havent had the time to work on it much anyway. I have some ideas and found a tutorial about appending the fields. I am thinking of adding a "invisible" textview box to store the current string in, and add the number pressed to the end of that string and update it, then have it output to the textedit box of the calculator. It seems a roundabout way to do it, but hopefully it will work! — user1231255, Feb 28 '12 at 15:45
Well that should be in the code too, just append the contents of the EditText with the number ("" + num). — Jon, Feb 28 '12 at 17:57
Ok, I got it!! A big thanks to you, Jon! You were a great help! The solution was so simple, that I really feel like kicking myself. All I had to do was: EditText et = (EditText) findViewById(R.id.textedit); et.append("c"); I cannot believe how simple it was x( Thanks all! Question has been answered! — user1231255, Feb 29 '12 at 16:15
No worries! et.append() was on my mind too, which is basically my previous comment anyway. Good luck with your code. =) — Jon, Feb 29 '12 at 16:58

Calculator Problems - Android Programming

2 Answers2

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