Android Studio App : Im creating a basic application, in android studio. The code seems to be okay. However, when I run it in Emulator the app doesn't work. Please help me determine what I am missing. 
CODE :package com.example.claudia.myapplication;


        import android.os.Bundle;
    import android.support.v7.app.ActionBarActivity;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.TextView;
    import android.widget.Toast;

    public class MainActivity extends ActionBarActivity {


    @Override// Calculating Body mass index
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final Button button_Calc = (Button) findViewById(R.id.button_Calc);
        final EditText Field_Weight = (EditText)      findViewById(R.id.Field_Weight);
        final EditText Field_Height = (EditText) findViewById(R.id.Field_Height);
        final TextView View_Result = (TextView) findViewById(R.id.View_Results);
        final TextView View_Msg = (TextView) findViewById(R.id.View_Msg);

        button_Calc.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double weight;
                double height;
                double bmi;
                String msg = "";

                if (Field_Height.getText().toString().equals("") || Field_Weight.getText().toString().equals("")) {
                    Toast.makeText(getApplicationContext(), "No Valid Values!", Toast.LENGTH_LONG).show();


                    weight = Double.parseDouble(Field_Weight.getText().toString());
                    height = Double.parseDouble(Field_Height.getText().toString());

                    bmi = height * height;
                    bmi = weight / bmi;

                    View_Result.setText(String.valueOf(bmi));

                    if (bmi < 18.5) {
                        msg = "Client is Under Weight :(";
                    } else if (bmi > 18.5 && bmi < 25) {
                        msg = "Normal :)";
                    } else if (bmi > 25) {
                        msg = "Client is Overweight";
                    }
                    View_Msg.setText(msg);

                }


            }
        });


        // Calculating Calories in and out
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            final Button Cal_calc = (Button) findViewById(R.id.Cal_calc);
            final EditText field_cal = (EditText) findViewById(R.id.field_Cal);
            final EditText field_burn = (EditText) findViewById(R.id.field_burn);
            final TextView View_calRes = (TextView) findViewById(R.id.View_calRes);
            final TextView View_calMsg = (TextView) findViewById(R.id.view_calMsg);

            Cal_calc.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    double calories;
                    double burn;
                    double CaloricTotal;
                    String calMsg = "";

                    if (field_cal.getText().toString().equals("") || field_burn.getText().toString().equals("")) {
                        Toast.makeText(getApplicationContext(), "No Valid Values!", Toast.LENGTH_LONG).show();


                        calories = Double.parseDouble(field_cal.getText().toString());
                        burn = Double.parseDouble(field_burn.getText().toString());

                        CaloricTotal = calories * calories;
                        CaloricTotal = burn / CaloricTotal;

                        View_calRes.setText(String.valueOf(CaloricTotal));

                        if (CaloricTotal < 1500) {
                            calMsg = "Client Needs to consume more Calories :(";
                        } else if (CaloricTotal > 1500 && CaloricTotal < 2000) {
                            calMsg = "Client is Normal :)";
                        } else if (CaloricTotal > 2000) {
                            calMsg = "Client Needs to consume less calories";
                        }
                        View_calMsg.setText(calMsg);

                    }



                }
            });
        }
        }}
RUN Error::


11/01 22:57:40: Launching app
$ adb shell am start -n "com.example.claudia.myapplication/com.example.claudia.myapplication.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Connected to process 3591 on device emulator-5554
I/art: Not late-enabling -Xcheck:jni (already on)
W/art: Unexpected CPU variant for X86 using defaults: x86
W/System: ClassLoader referenced unknown path: /data/app/com.example.claudia.myapplication-2/lib/x86
I/InstantRun: Instant Run Runtime started. Android package is com.example.claudia.myapplication, real application class is null.

              [ 11-01 22:53:09.592  1515: 1538 D/         ]
              HostConnection::get() New Host Connection established 0x95618500, tid 1538
W/System: ClassLoader referenced unknown path: /data/app/com.example.claudia.myapplication-2/lib/x86
W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.example.claudia.myapplication, PID: 3591
                  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.claudia.myapplication/com.example.claudia.myapplication.MainActivity}: java.lang.IllegalStateException: Already attached
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
                      at android.app.ActivityThread.-wrap12(ActivityThread.java)
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
                      at android.os.Handler.dispatchMessage(Handler.java:102)
                      at android.os.Looper.loop(Looper.java:154)
                      at android.app.ActivityThread.main(ActivityThread.java:6077)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
                   Caused by: java.lang.IllegalStateException: Already attached
                      at android.support.v4.app.FragmentManagerImpl.attachController(FragmentManager.java:2132)
                      at android.support.v4.app.FragmentController.attachHost(FragmentController.java:104)
                      at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:315)
                      at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:85)
                      at com.example.claudia.myapplication.MainActivity.onCreate(MainActivity.java:63)
                      at android.app.Activity.performCreate(Activity.java:6664)
                      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
                      at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:154) 
                      at android.app.ActivityThread.main(ActivityThread.java:6077) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
Application terminated.