title: Simple Android Calculator
body: <p>I am trying to build a simple calculator. Following is the activity file:</p>
  
  <pre><code> package com.example.calcsimple;
  
  
  import android.os.Bundle;
  import android.annotation.SuppressLint;
  import android.app.Activity;
  import android.view.Menu; 
  import android.view.View;
  import android.widget.Button;
  import android.widget.TextView;
  import android.view.View.OnClickListener;
  
  
  public class MainActivity extends Activity {
  
  Button btnClr , btn0 , btn1 , btn2 , btn3 , btn4, btn5 , btn6 , btn7 , btn8 , btn9 , btnAdd , btnSub , btnMul , btnDiv , btnEq;
  TextView textView1 ; 
  double i1 , i2 , result=0;
  boolean newValue = false;
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      textView1 = (TextView) findViewById(R.id.textView1);
  
      btnClr = (Button) findViewById(R.id.btnClr);
      btn0 = (Button) findViewById(R.id.btn0);
      btn1 = (Button) findViewById(R.id.btn1);
      btn2 = (Button) findViewById(R.id.btn2);
      btn3 = (Button) findViewById(R.id.btn3);
      btn4 = (Button) findViewById(R.id.btn4);
      btn5 = (Button) findViewById(R.id.btn5);
      btn6 = (Button) findViewById(R.id.btn6);
      btn7 = (Button) findViewById(R.id.btn7);
      btn8 = (Button) findViewById(R.id.btn8);
      btn9 = (Button) findViewById(R.id.btn9);
      btnAdd = (Button) findViewById(R.id.btnAdd);
      btnSub = (Button) findViewById(R.id.btnSub);
      btnMul = (Button) findViewById(R.id.btnMul);
      btnDiv = (Button) findViewById(R.id.btnDiv);
      btnEq = (Button) findViewById(R.id.btnEq);
  
      btn0.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
              textView1.append("0");
          }
      });
  
      btn1.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("1");
               else
                   textView1.setText(textView1.getText().toString() +  "1");
  
               newValue = false;
          }
      });
  
      btn2.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("2");
               else
                   textView1.setText(textView1.getText().toString() +  "2");
  
               newValue = false;
          }
      });
  
      btn3.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("3");
               else
                   textView1.setText(textView1.getText().toString() +  "3");
  
               newValue = false;
          }
      });
  
      btn4.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("4");
               else
                   textView1.setText(textView1.getText().toString() +  "4");
  
               newValue = false;
          }
      });
  
      btn5.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("5");
               else
                   textView1.setText(textView1.getText().toString() +  "5");
  
               newValue = false;
          }
      });
  
      btn6.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("6");
               else
                   textView1.setText(textView1.getText().toString() +  "6");
  
               newValue = false;
          }
      });
  
      btn7.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("7");
               else
                   textView1.setText(textView1.getText().toString() +  "7");
  
               newValue = false;
          }
      });
  
      btn8.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("8");
               else
                   textView1.setText(textView1.getText().toString() +  "8");
  
               newValue = false;
          }
      });
  
      btn9.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
               if(newValue == true)
                   textView1.setText("9");
               else
                   textView1.setText(textView1.getText().toString() +  "9");
  
               newValue = false;
          }
      });
  
  
      btnAdd.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
              i1 = Double.parseDouble(textView1.getText().toString());
              textView1.setText("");
              result = result + i1;
              textView1.setText(Double.toString(result));
              newValue=true ;  
  
  
          }
      });
  
      btnSub.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
              i1 = Double.parseDouble(textView1.getText().toString());
              result = result - i1;
              textView1.setText(Double.toString(result));
              newValue=true ;  
              textView1.setText("");
          }
      });
  
      btnMul.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
              i1 = Double.parseDouble(textView1.getText().toString());
              result = result * i1;
              textView1.setText(Double.toString(result));
              newValue=true ;  
              textView1.setText("");
          }
      });
  
      btnDiv.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
              i1 = Double.parseDouble(textView1.getText().toString());
              result = result / i1;
              textView1.setText(Double.toString(result));
              newValue=true ;  
              textView1.setText("");
  
          }
      });
  
      btnEq.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
              textView1.setText(Double.toString(result));
          }
      });
  
      btnClr.setOnClickListener(new OnClickListener(){
          @Override
          public void onClick(View v) {
  
              textView1.setText("");
              newValue=true;
              result = 0 ;
              i1=0;
          }
      });
  
      }
  
  
  }
  </code></pre>
  
  <p>Following is the XML layout file:</p>
  
  <pre><code>&lt;AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent" &gt;
  
  &lt;Button
      android:id="@+id/btn1"
      android:layout_width="44dp"
      android:layout_height="wrap_content"
      android:layout_x="6dp"
      android:layout_y="109dp"
      android:text="1" /&gt;
  
  &lt;Button
      android:id="@+id/btn2"
      android:layout_width="48dp"
      android:layout_height="wrap_content"
      android:layout_x="88dp"
      android:layout_y="108dp"
      android:text="2" /&gt;
  
  &lt;Button
      android:id="@+id/btn3"
      android:layout_width="44dp"
      android:layout_height="wrap_content"
      android:layout_x="174dp"
      android:layout_y="106dp"
      android:text="3" /&gt;
  
  &lt;Button
      android:id="@+id/btn4"
      android:layout_width="45dp"
      android:layout_height="wrap_content"
      android:layout_x="6dp"
      android:layout_y="184dp"
      android:text="4" /&gt;
  
  &lt;TextView
      android:id="@+id/textView1"
      android:layout_width="match_parent"
      android:layout_height="30dp"
      android:layout_x="0dp"
      android:layout_y="4dp"
      android:text="" /&gt;
  
  &lt;Button
      android:id="@+id/btn5"
      android:layout_width="45dp"
      android:layout_height="wrap_content"
      android:layout_x="92dp"
      android:layout_y="186dp"
      android:text="5" /&gt;
  
  &lt;Button
      android:id="@+id/btn6"
      android:layout_width="45dp"
      android:layout_height="wrap_content"
      android:layout_x="175dp"
      android:layout_y="180dp"
      android:text="6" /&gt;
  
  &lt;Button
      android:id="@+id/btn7"
      android:layout_width="44dp"
      android:layout_height="wrap_content"
      android:layout_x="9dp"
      android:layout_y="261dp"
      android:text="7" /&gt;
  
  &lt;Button
      android:id="@+id/btn8"
      android:layout_width="44dp"
      android:layout_height="wrap_content"
      android:layout_x="94dp"
      android:layout_y="264dp"
      android:text="8" /&gt;
  
  &lt;Button
      android:id="@+id/btn9"
      android:layout_width="46dp"
      android:layout_height="wrap_content"
      android:layout_x="176dp"
      android:layout_y="263dp"
      android:text="9" /&gt;
  
  &lt;Button
      android:id="@+id/btn0"
      android:layout_width="45dp"
      android:layout_height="wrap_content"
      android:layout_x="96dp"
      android:layout_y="348dp"
      android:text="0" /&gt;
  
  &lt;Button
      android:id="@+id/btnAdd"
      android:layout_width="45dp"
      android:layout_height="wrap_content"
      android:layout_x="248dp"
      android:layout_y="105dp"
      android:text="+" /&gt;
  
  &lt;Button
      android:id="@+id/btnSub"
      android:layout_width="43dp"
      android:layout_height="wrap_content"
      android:layout_x="249dp"
      android:layout_y="181dp"
      android:text="-" /&gt;
  
  &lt;Button
      android:id="@+id/btnMul"
      android:layout_width="43dp"
      android:layout_height="wrap_content"
      android:layout_x="248dp"
      android:layout_y="267dp"
      android:text="X" /&gt;
  
  &lt;Button
      android:id="@+id/btnDiv"
      android:layout_width="44dp"
      android:layout_height="wrap_content"
      android:layout_x="248dp"
      android:layout_y="347dp"
      android:text="/" /&gt;
  
  &lt;Button
      android:id="@+id/btnEq"
      android:layout_width="44dp"
      android:layout_height="wrap_content"
      android:layout_x="176dp"
      android:layout_y="347dp"
      android:text="=" /&gt;
  
  &lt;Button
      android:id="@+id/btnClr"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_x="12dp"
      android:layout_y="346dp"
      android:text="Clear" /&gt;
  
  &lt;/AbsoluteLayout&gt;
  </code></pre>
  
  <p>Now the problem is that I'm not finding any way to receive and store the second operand from the user.</p>