Question

Im attempting a tutorial for a second time and getting the same errors that i wasnt able to resolve. Im getting red underlines on MainActivityTextview.
I assigned a text box an id of “MainActivityTextview” and now im trying to set the text it it.
Simple right? But I cant get it to work. Am I missing an import?
Thanks

MainActivity.java

package com.Proteintracker;

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

public class MainActivity extends Activity {

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

    TextView textView = (TextView) findViewById(android.R.id.MainActivityTextview);
    textView.setText("hello world");
}


}

r.java

package com.Proteintracker;

public final class R {
public static final class attr {
}
public static final class drawable {
    public static final int ic_action_search=0x7f020000;
    public static final int ic_launcher=0x7f020001;
}
public static final class id {
    public static final int MainActivityTextview=0x7f070000;
    public static final int menu_settings=0x7f070001;
}
public static final class layout {
    public static final int activity_main=0x7f030000;
}
public static final class menu {
    public static final int activity_main=0x7f060000;
}
public static final class string {
    public static final int app_name=0x7f040000;
    public static final int hello_world=0x7f040001;
    public static final int menu_settings=0x7f040002;
    public static final int title_activity_main=0x7f040003;
}
public static final class style {
    public static final int AppTheme=0x7f050000;
}
}

Activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

<TextView
    android:id="@+id/MainActivityTextview"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="@string/hello_world"
    tools:context=".MainActivity" />

</RelativeLayout>

Answer 1

TextView textView = (TextView) findViewById(R.id.MainActivityTextview);

Remove “android.”, it is your resource, not system.