Opening a Webpage in the Browser

Not too sure what is going on but I am getting the following errors:

JavaTester.java:1: package android.os does not exist import android.os.Bundle; ^ JavaTester.java:2: package android.view does not exist import android.view.View; ^ JavaTester.java:3: package android.view does not exist import android.view.ListView; ^ JavaTester.java:4: package android.content does not exist import android.content.Intent; ^ JavaTester.java:5: package android.net does not exist import android.net.Uri; ^ ./CustomListActivity.java:1: package android.os does not exist import android.os.Bundle; ^ ./CustomListActivity.java:2: package android.widget does not exist import android.widget.ArrayAdapter; ^ ./CustomListActivity.java:3: package android.view does not exist import android.view.View; ^ ./CustomListActivity.java:4: package android.view does not exist import android.view.ListView; ^ ./CustomListActivity.java:5: package android.content does not exist import android.content.Intent; ^ ./CustomListActivity.java:6: package android.net does not exist import android.net.Uri; ^ ./ListActivity.java:1: package android.os does not exist import android.os.Bundle; ^ ./ListActivity.java:2: package android.widget does not exist import android.widget.ArrayAdapter; ^ ./ListActivity.java:3: package android.app does not exist import android.app.Activity; ^ ./ListActivity.java:4: package android.view does not exist import android.view.View; ^ ./ListActivity.java:5: package android.view does not exist import android.view.ListView; ^ ./ListActivity.java:7: cannot find symbol symbol: class Activity public class ListActivity extends Activity { ^ ./CustomListActivity.java:13: cannot find symbol symbol : class Bundle location: class CustomListActivity public void onCreate(Bundle savedInstanceState) { ^ ./CustomListActivity.java:22: cannot find symbol symbol : class ListView location: class CustomListActivity protected void onListItemClick(ListView l, View v, int position, long id) { ^ ./CustomListActivity.java:22: cannot find symbol symbol : class View location: class CustomListActivity protected void onListItemClick(ListView l, View v, int position, long id) { ^ ./ListActivity.java:13: cannot find symbol symbol : class ArrayAdapter location: class ListActivity public void setListAdapter(ArrayAdapter adapter) { ^ ./ListActivity.java:17: cannot find symbol symbol : class ListView location: class ListActivity protected void onListItemClick(ListView l, View v, int position, long id) { ^ ./ListActivity.java:17: cannot find symbol symbol : class View location: class ListActivity protected void onListItemClick(ListView l, View v, int position, long id) { ^ JavaTester.java:28: cannot find symbol symbol : class ListView location: class JavaTester activity.onListItemClick(new ListView(), new View(), 0, 1); ^ JavaTester.java:28: cannot find symbol symbol : class View location: class JavaTester activity.onListItemClick(new ListView(), new View(), 0, 1); ^ JavaTester.java:34: cannot find symbol symbol : class Bundle location: class JavaTester activity.onCreate(new Bundle()); ^ ./CustomListActivity.java:15: cannot find symbol symbol : method setContentView(int) location: class CustomListActivity setContentView(R.layout.activity_custom_list); ^ ./CustomListActivity.java:17: cannot find symbol symbol : class ArrayAdapter location: class CustomListActivity ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, mUrls); ^ ./CustomListActivity.java:17: cannot find symbol symbol : class ArrayAdapter location: class CustomListActivity ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, mUrls); ^ ./CustomListActivity.java:17: package android.R does not exist ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, mUrls); ^ 30 errors

If I do not change anything in my code which is shown below and click Recheck Work about 3-5 times it says I'm correct.

import android.os.Bundle; import android.widget.ArrayAdapter; import android.view.View; import android.view.ListView; import android.content.Intent; import android.net.Uri;

public class CustomListActivity extends ListActivity {

protected String[] mUrls = { "http://www.teamtreehouse.com", "http://developer.android.com", "http://www.github.com" };

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_custom_list);

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mUrls);
    setListAdapter(adapter);
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);
}

}