Android application has stopped working- Eclipse

Issue

I'm beginner in android development. I get this error message both in emulator and my real Android device. Please help me !!

public class MainActivity extends ActionBarActivity {
     Button btn1;
     TextView tv1;
     EditText edt1;
     String msj= "d";       

double n = Double.valueOf(edt1 . getText().toString());
double a = (1 / (Math.sqrt(5))); 
double b = ((1+(Math.sqrt(5)))/2); 
double c = ((1-(Math.sqrt(5)))/2); 
double i = a * ((Math.pow(b,n)) - (Math.pow(c,n)));
String k = String.valueOf(i);

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);   

   setContentView(R.layout.activity_main);
    btn1 = (Button) findViewById(R.id.btn1);
    final TextView tv1 = (TextView) findViewById(R.id.tv1);
    final EditText edt1 = (EditText) findViewById(R.id.edt1);

    btn1.setOnClickListener(new OnClickListener() {         
        @Override
        public void onClick(View v) {               
            msj = edt1.getText().toString();
            tv1.setText( k );               
        }
    });

}

@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;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

}

XML Code;

<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="com.example.fibonacci.MainActivity" >

<EditText
    android:id="@+id/edt1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:ems="10"
    android:hint="@string/girdi"
    android:inputType="number" >

</EditText>

<Button
    android:id="@+id/btn1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/edt1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="60dp"
    android:text="@string/buton" />

<TextView
    android:id="@+id/tv1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignLeft="@+id/edt1"
    android:layout_below="@+id/btn1"
    android:layout_marginTop="37dp"
    android:text="@string/cikti" />

</RelativeLayout>

I could't able to post the Log cat. Because of character limitation. HEre is the LogCat:

    0-13 17:10:48.907: I/Choreographer(380): Skipped 30 frames!  The application may be doing too much work on its main thread.
10-13 17:10:48.927: E/AndroidRuntime(1021): FATAL EXCEPTION: main
10-13 17:10:48.927: E/AndroidRuntime(1021): Process: com.example.fibonacci, PID: 1021
10-13 17:10:48.927: E/AndroidRuntime(1021): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.fibonacci/com.example.fibonacci.MainActivity}: java.lang.NullPointerException
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.os.Handler.dispatchMessage(Handler.java:102)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.os.Looper.loop(Looper.java:136)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.ActivityThread.main(ActivityThread.java:5017)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at java.lang.reflect.Method.invokeNative(Native Method)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at java.lang.reflect.Method.invoke(Method.java:515)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at dalvik.system.NativeStart.main(Native Method)
10-13 17:10:48.927: E/AndroidRuntime(1021): Caused by: java.lang.NullPointerException
10-13 17:10:48.927: E/AndroidRuntime(1021):     at com.example.fibonacci.MainActivity.<init>(MainActivity.java:20)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at java.lang.Class.newInstanceImpl(Native Method)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at java.lang.Class.newInstance(Class.java:1208)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
10-13 17:10:48.927: E/AndroidRuntime(1021):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
10-13 17:10:48.927: E/AndroidRuntime(1021):     ... 11 more
10-13 17:10:48.977: I/Choreographer(380): Skipped 47 frames!  The application may be doing too much work on its main thread.
10-13 17:10:48.977: W/ActivityManager(380):   Force finishing activity com.example.fibonacci/.MainActivity
10-13 17:10:49.387: I/WindowManager(380): Screenshot max retries 4 of Token{b2f8e630 ActivityRecord{b2f8e4d0 u0 com.example.fibonacci/.MainActivity t3 f}} appWin=Window{b30e4a38 u0 Starting com.example.fibonacci} drawState=4
10-13 17:10:49.387: W/WindowManager(380): Screenshot failure taking screenshot for (320x480) to layer 21010

Thanks for your help.

Solution

As @Sunil made a point, this is probably gonna get you closer to your code to work. You have to calculate in your onClick method.

public class MainActivity extends ActionBarActivity {
    Button btn1;
    TextView tv1;
    EditText edt1;
    String msj= "d";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1 = (Button) findViewById(R.id.btn1);
        tv1 = (TextView) findViewById(R.id.tv1);
        edt1 = (EditText) findViewById(R.id.edt1);
        btn1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                double n = Double.valueOf(edt1.getText().toString());
                double a = (1 / (Math.sqrt(5))); 
                double b = ((1+(Math.sqrt(5)))/2); 
                double c = ((1-(Math.sqrt(5)))/2); 
                double i = a * ((Math.pow(b,n)) - (Math.pow(c,n)));
                String k = String.valueOf(i);
                msj = edt1.getText().toString();
                tv1.setText( k );               
            }
        });

    }

}

Answered By - Marija Milosevic