Kalkulator Android Sederhana

Kalkulator Android merupakan aplikasi pengolah angka(kalkulator) sederhana berbasis android. Ini adalah aplikasi android pertama yang aku buat. 

Aplikasi ini terdiri dari dua buah kelas yaitu :

1. KalkulatorEngine
2. MainActivity

Berikut ini adalah lampiran source codenya:

1. Kalkulator Engine

public class KalkulatorEngine {

    double value, keep;
    char toDo;
 
    //method operasi
    public void operation(char op){
        keep = value;
        value = 0;
        toDo = op;
    }
 
    //method penjumlahan
    public void add(){
        operation('+');
    }

    //method pengurangan
    public void substract(){
        operation('-');
    }

    //method perkalian
    public void multiply(){
        operation('*');
    }

    //method pembagian
    public void divide(){
        operation('/');
    }

    //method perhitungan
    public void compute(){
        if(toDo == '+')
            value = keep + value;
        else if(toDo == '-')
            value = keep - value;
        else if(toDo == '*')
            value = keep * value;
        else if(toDo == '/')
            value = keep / value;
        keep = 0;
    }

    //mereset nilai
    public void clear(){
        value = 0;
        keep = 0;
    }

    //menentukan digit
    public void digit(int x){
        value = value*10 + x;
    }

    //method menampilkan
    public double display(){
        return (value);
    }
}

2. MainActivity

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


public class MainActivity extends Activity {
 
 //membuat button
 Button satu, dua, tiga, empat, lima, 
     enam, tujuh, delapan, sembilan, nol;
 
 Button add, sub, div, mull, samadengan, clear;
 //membuat textfield
 EditText display;
    
 KalkulatorEngine kalkulator = new KalkulatorEngine();
 
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        //menginisialisasi button berdasarkan id di xml
        satu = (Button) findViewById(R.id.button1);
        dua = (Button) findViewById(R.id.button2);
        tiga = (Button) findViewById(R.id.button3);
        empat = (Button) findViewById(R.id.button4);
        lima = (Button) findViewById(R.id.button5);
        enam = (Button) findViewById(R.id.button6);
        tujuh = (Button) findViewById(R.id.button7);
        delapan = (Button) findViewById(R.id.button8);
        sembilan = (Button) findViewById(R.id.button9);
        nol = (Button) findViewById(R.id.button10);
        samadengan = (Button) findViewById(R.id.button12);
        clear = (Button) findViewById(R.id.button11);
        add = (Button) findViewById(R.id.button_tambah);
        sub = (Button) findViewById(R.id.button_kurang);
        mull = (Button) findViewById(R.id.button_kali);
        div = (Button) findViewById(R.id.button_bagi);
        
        display = (EditText) findViewById(R.id.text1);
        
        satu.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(1);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        dua.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(2);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        tiga.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(3);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        empat.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(4);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        lima.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(5);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        enam.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(6);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        tujuh.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(7);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        delapan.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(8);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        sembilan.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(9);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        nol.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.digit(0);
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        add.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.add();
    display.setText("+");
   }
  });
        sub.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.substract();
    display.setText("-");
   }
  });
        mull.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.multiply();
    display.setText("*");
   }
  });
        div.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.divide();
    display.setText("/");
   }
  });
        samadengan.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.compute();
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
        clear.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    kalkulator.clear();
    String angka = String.valueOf(kalkulator.display());
    display.setText(angka);
   }
  });
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

source dapat di download disini