Android : Android : intent putExtra causing error

I have 2 activities transferring a String variable from on to the other with a putExtra intent. I am using two buttons in the onclick method of the sender activity, one button retrieves a word from an array in another class and sends it to the recieving activity. The other button sends the String from an editText field. However, i am getting an error, any help appreciated.

Sending class

@Override
public void onClick(View v) {

    if (v.getId() == R.id.OnePlayer) {

        Intent myIntent = new Intent(TitleScreen.this, MainActivity.class);
        myIntent.putExtra("gameWord", wordDiff.getRandomWord());
        startActivity(myIntent);
        finish();

    } else if (v.getId() == R.id.TwoPlayer) {
        onePlayer.setVisibility(View.GONE);
        twoPlayer.setVisibility(View.GONE);
        inputWord.setVisibility(View.VISIBLE);
        play.setVisibility(View.VISIBLE);

    } else if (v.getId() == R.id.Continue){

        // if no word is inputed then game will not start 
        if(inputWord.getText().toString().trim().length() == 0){
            Toast.makeText(getApplicationContext(), "Enter a word",
                    Toast.LENGTH_SHORT).show();
        } else{
            Intent myIntent = new Intent(TitleScreen.this, MainActivity.class);
            myIntent.putExtra("gameWord", inputWord.getText().toString());
            startActivity(myIntent);
            finish();
        }
    }

}

receiving activity within the onCreate method

    Intent myIntent = getIntent();
    secretWord = myIntent.getStringExtra("gameWord");

here is the logCat

Shutting down VM
FATAL EXCEPTION: main
Process: com.example.hunglikeanandroid, PID: 3431
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.hunglikeanandroid/com.example.hunglikeanandroid.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
atandroid.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at com.example.hunglikeanandroid.MainActivity.<init>(MainActivity.java:35)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1572)
at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)