activity_main cannot be resolved or is not a field

package com.zigax.crystalball2;

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

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_item);
        //Declare our view variables
        final TextView anwserLabel = (TextView) findViewById(R.id.text1);
        Button getAnwserButton = (Button) findViewById(R.id.button1);

        getAnwserButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                String anwser = "Yes";
                anwserLabel.setText(anwser);
            }
        });
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

}