package zero.zd.zquestionnaire;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class QnaBuilderActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_qna_builder);
    }
}

package zero.zd.zquestionnaire;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuItem;

public class QnaBuilderActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_qna_builder);
        if (getSupportActionBar() != null) {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        }

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

add back button