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-trac

Answer 1

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>

Answer 2

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?