Android Helper By Saroj Khatiwoda: Very Basic Android Calculator

Note:This calculator simply performs very basic additon subtraction multiplication and division, The data type is limited only to integer, It perorms well even though there little errors on data validation part.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_weight="1"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"    android:orientation="vertical">

<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_weight="1"

android:orientation="vertical">
 <EditText

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:id="@+id/editText1"

android:layout_weight="1" />

<EditText

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:id="@+id/editText2"

android:layout_weight="1" />

</LinearLayout>

<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal"

android:layout_weight="1">
</LinearLayout>
<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal"

android:layout_weight="1">
<Button

android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="7"
android:onClick="btnNumOnClick" />
<Button

android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="8"
android:onClick="btnNumOnClick" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="9"
android:onClick="btnNumOnClick" />

<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="/"
android:onClick="btnOperators" />

</LinearLayout>
<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal"

android:layout_weight="1">
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="4"
android:onClick="btnNumOnClick" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="5"
android:onClick="btnNumOnClick" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="6"
android:onClick="btnNumOnClick" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="*"
android:onClick="btnOperators" />

</LinearLayout>
<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal">
<Button

android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="1"
android:onClick="btnNumOnClick" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="2"
android:onClick="btnNumOnClick" />
<Button

android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="3"
android:onClick="btnNumOnClick" />
<Button

android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="-"
android:onClick="btnOperators" />

</LinearLayout>
<LinearLayout

 android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal" >
 <Button
 android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="0"
android:onClick="btnNumOnClick" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="."

android:id="@+id/button2" />
<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="="

android:id="@+id/button3"

android:onClick="btnEqualClick" />

<Button
android:layout_width="0dp"

android:layout_weight="1"

android:layout_height="wrap_content"

android:text="+"

android:id="@+id/button4"

android:onClick="btnOperators" />

</LinearLayout>
<Button

 android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Back space"

android:id="@+id/button"

android:layout_gravity="center_horizontal"

android:layout_weight="1"

android:onClick="onBackSpaceClick" />

</LinearLayout>

Here Basic  concepts of string manipulation is used in MainActivity.java,

The Code is as follows

 
import android.app.Activity;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import java.util.ArrayList;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

String strTemp1,strTemp2;    
@Override    protected void onCreate(Bundle savedInstanceState) 
{
super.onCreate(savedInstanceState);        
setContentView(R.layout.activity_main);    
}


public void btnNumOnClick(View v)
    {

        Button button=(Button) v;        
strTemp1=button.getText().toString();
         if(strTemp2==null)
         {
          strTemp2=strTemp1+"";         }
        else         {
             strTemp2=strTemp2+strTemp1;         }

        TextView et=(TextView) findViewById(R.id.editText2);        
et.setText(strTemp2);    }


    public void btnOperators(View v)
    {
        strTemp2=null;        
strTemp1=null;        
Button button=(Button) v;        
strTemp1=button.getText().toString();        
TextView view=(TextView) findViewById(R.id.editText2);        
strTemp2=view.getText().toString();        
strTemp2=strTemp2+strTemp1;        
TextView et=(TextView) findViewById(R.id.editText2);        
et.setText(strTemp2);
    }


    public void btnEqualClick(View v)
    {
         if (strTemp2.contains("+"))
        {
            Calculate(strTemp2,"+" );        }
        else if(strTemp2.contains("-"))
         {
           Calculate(strTemp2,"-");         }
        else if(strTemp2.contains("*"))
         {
             Calculate(strTemp2,"*");         }
        else if(strTemp2.contains("/"))
         {
             Calculate(strTemp2,"/" ) ;         }
    }

    public void  Calculate(String strTemp2,String Sign)
    {
        int index1=strTemp2.indexOf(Sign);        
int index2=strTemp2.length();        
String firstValue;        
String secondValue;        
int Result;        
TextView tv=(TextView) findViewById(R.id.editText1);        
firstValue=strTemp2.substring(0,index1);        
secondValue=strTemp2.substring(index1+1,index2);        
int FirstValue= Integer.parseInt(firstValue);        
int SecondValue=Integer.parseInt(secondValue);
        switch (Sign)
        {
            case "+": Result=FirstValue+SecondValue;                
tv.setText(String.valueOf(Result));                     
break;            
case "-":Result=FirstValue-SecondValue;                
tv.setText(String.valueOf(Result));                    
break;            
case "*": Result=FirstValue*SecondValue;                
tv.setText(String.valueOf(Result));                    
 break;            
case  "/": Result=FirstValue/SecondValue;                
tv.setText(String.valueOf(Result));                      
break;        
}

}

public void onBackSpaceClick(View v)
    {

        strTemp2=strTemp2.replace(strTemp2.substring(strTemp2.length()-1),"") ;        
TextView et=(TextView) findViewById(R.id.editText2);       
 et.setText(strTemp2);
    }

}

Android Helper By Saroj Khatiwoda

Saturday, July 4, 2015

Very Basic Android Calculator

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