If you were unable to hear everything i said in the video above, below is the source code of the calculator application that was built.
Place this code in the layout of the application
activity_main.xml
`
<RelativeLayout 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" 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"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceLarge" android:text="My Basic Calculator" android:id="@+id/textView" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:textColor="#008888" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceMedium" android:text="First Number" android:id="@+id/textView2" android:layout_below="@+id/textView" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" android:layout_marginTop="30dp" /> <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:inputType="number" android:ems="10" android:id="@+id/etFirstNumber" android:layout_below="@+id/textView2" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceMedium" android:text="Second Number" android:id="@+id/textView3" android:layout_below="@+id/etFirstNumber" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" /> <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:inputType="number" android:ems="10" android:id="@+id/etSecondNumber" android:layout_below="@+id/textView3" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" /> <LinearLayout android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_below="@+id/etSecondNumber" android:layout_alignParentLeft="true" android:layout_alignParentStart="true"> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="+" android:id="@+id/btnAdd" android:background="#51ff00" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="-" android:id="@+id/btnSubtract" android:background="#ff0000" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="/" android:id="@+id/btnDivide" android:background="#ffb300" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="*" android:id="@+id/btnMultiply" android:background="#00ffe6" /> </LinearLayout> <LinearLayout android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_alignParentRight="true" android:layout_alignParentEnd="true"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textAppearance="?android:attr/textAppearanceLarge" android:id="@+id/tvResult" android:layout_centerVertical="true" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" android:textColor="#0000FF" android:layout_marginTop="40dp" /> </LinearLayout> </RelativeLayout>
Next, place this code in the MainActivity of the application
MainActivity.java
package com.basiccalc.mybasiccalculator; import android.support.v7.app.ActionBarActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class MainActivity extends ActionBarActivity implements View.OnClickListener { private Button btnAdd,btnsub,btndivide,btnmul; private TextView tvresult; private EditText etfirst,etsecond; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); init(); } private void init() { btnAdd =(Button)findViewById(R.id.btnAdd); btnsub = (Button)findViewById(R.id.btnSubtract); btndivide = (Button)findViewById(R.id.btnDivide); btnmul = (Button)findViewById(R.id.btnMultiply); etfirst = (EditText)findViewById(R.id.etFirstNumber); etsecond =(EditText)findViewById(R.id.etSecondNumber); tvresult = (TextView)findViewById(R.id.tvResult); btnAdd.setOnClickListener(this); btnsub.setOnClickListener(this); btndivide.setOnClickListener(this); btnmul.setOnClickListener(this); } @Override public void onClick(View view) { String num1 = etfirst.getText().toString(); String num2 = etsecond.getText().toString(); switch(view.getId()){ case R.id.btnAdd: int addition = Integer.parseInt(num1) + Integer.parseInt(num2); tvresult.setText(String.valueOf(addition)); break; case R.id.btnSubtract: int subtraction = Integer.parseInt(num1) - Integer.parseInt(num2); tvresult.setText(String.valueOf(subtraction)); break; case R.id.btnDivide: try{ int division = Integer.parseInt(num1) / Integer.parseInt(num2); tvresult.setText(String.valueOf(division)); }catch(Exception e){ tvresult.setText("Cannot DIVIDE!"); } break; case R.id.btnMultiply: int multiply = Integer.parseInt(num1) * Integer.parseInt(num2); tvresult.setText(String.valueOf(multiply)); break; } } }