[Java for Android App Development] [==)BULLET(==]:
Changed thing in accordance with video but still getting fc.

If possible could anyone paste the correct codes in my style?

BTW here are the code

strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

<string name="app_name">CalcPlus</string>
<string name="action_settings">Settings</string>
<string name="hello_world">Hello world!</string>
<string name="btnp">+</string>
<string name="btns">-</string>
<string name="btnm">*</string>
<string name="btnd">/</string>
<string name="txt2">Enter number 2 here</string>
<string name="txt1">Enter number 1 here</string>
<string name="txta">Result</string>

</resources>

MainActivity.java

package com.ptx.calcplus;

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

public class MainActivity extends Activity {
private EditText txtN1;
private EditText txtN2;
private EditText txtAn;
Button Add,Sub,Div,Mul;
double a=Double.parseDouble(txtN1.getText().toString());
double b=Double.parseDouble(txtN2.getText().toString());
double c=0;
[MENTION=439709]override[/MENTION]
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Add= (Button) findViewById(R.id.btnAdd);
Sub= (Button) findViewById(R.id.btnSub);
Div= (Button) findViewById(R.id.btnDiv);
Mul= (Button) findViewById(R.id.btnMul);
txtN1= (EditText) findViewById(R.id.txtNum1);
txtN2= (EditText) findViewById(R.id.txtNum2);
txtAn= (EditText) findViewById(R.id.txtAns);
Add.setOnClickListener(new View.OnClickListener() {

[MENTION=439709]override[/MENTION]
public void onClick(View arg0) {
c=a+b;
txtAn.setText(""+c);
}
});
Sub.setOnClickListener(new View.OnClickListener() {

[MENTION=439709]override[/MENTION]
public void onClick(View arg0) {
c=a+b;
txtAn.setText(""+c);
}
});
Mul.setOnClickListener(new View.OnClickListener() {

[MENTION=439709]override[/MENTION]
public void onClick(View arg0) {
c=a+b;
txtAn.setText(""+c);
}
});
Div.setOnClickListener(new View.OnClickListener() {

[MENTION=439709]override[/MENTION]
public void onClick(View arg0) {
c=a+b;
txtAn.setText(""+c);
}
});
}

[MENTION=439709]override[/MENTION]
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;
}

}

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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<Button
android:id="@+id/btnMul"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/btnSub"
android:layout_alignBottom="@+id/btnSub"
android:layout_alignParentLeft="true"
android:text="@string/btnm"
android:onClick="mul" />

<Button
android:id="@+id/btnSub"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginBottom="127dp"
android:layout_toRightOf="@+id/btnMul"
android:text="@string/btns"
android:onClick="sub" />

<Button
android:id="@+id/btnAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/btnSub"
android:layout_alignBottom="@+id/btnSub"
android:layout_toRightOf="@+id/btnSub"
android:text="@string/btnp"
android:onClick="add" />

<Button
android:id="@+id/btnDiv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/btnAdd"
android:layout_alignBottom="@+id/btnAdd"
android:layout_toRightOf="@+id/btnAdd"
android:text="@string/btnd"
android:onClick="div"/>

<EditText
android:id="@+id/txtNum2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/btnMul"
android:layout_alignLeft="@+id/btnMul"
android:layout_alignRight="@+id/btnDiv"
android:layout_marginBottom="90dp"
android:ems="10"
android:hint="@string/txt2"
android:inputType="numberDecimal" />

<EditText
android:id="@+id/txtNum1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/txtNum2"
android:layout_alignLeft="@+id/txtNum2"
android:layout_alignRight="@+id/txtNum2"
android:layout_marginBottom="39dp"
android:ems="10"
android:hint="@string/txt1"
android:inputType="numberDecimal" >

<requestFocus />
</EditText>

<EditText
android:id="@+id/txtAns"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/txtNum2"
android:layout_alignRight="@+id/btnDiv"
android:layout_below="@+id/btnMul"
android:layout_marginTop="40dp"
android:ems="10"
android:enabled="false"
android:hint="@string/txta"
android:linksClickable="false" />

</RelativeLayout>

Please please help me out!