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Android Build a Simple Android App (2014) Improving Our Code Dynamically Changing the Background Color

Hafeez Khan
Hafeez Khan
1,270 Points
Posted by Hafeez Khan
Hafeez Khan
1,270 Points

In my FunFactsActivity class, i keep getting three errors, all three of them being, cannot resolve symbol "R".

public class FunFactsActivity extends Activity {

private FactBook mFactBook = new FactBook();

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fun_facts);

    // Declare our View Variables and assign the Views from the layout file
    final TextView factLabel = (TextView) findViewById(R.id.factTextView);
    Button showFactButton = (Button) findViewById(R.id.ShowFactButton);
    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
                 String fact = mFactBook.getFact();

            //Update the label with our dynamic fact
            factLabel.setText(fact);

        }
    };
    showFactButton.setOnClickListener(listener);

}

}

Everything above is my current code, the errors are occurring where ever the "R" is, PLEASE HELP.

justindennison
justindennison
15,922 Points

Taking a look at your code, my first instinct is that 

Button showFactButton = (Button) findViewById(R.id.ShowFactButton);

should be

Button showFactButton = (Button) findViewById(R.id.showFactButton);

That may not be the error if you have set the button's id to ShowFactButton

I have a follow up question so maybe I can be of some more help, do you have all of those elements added to your layout using either the graphical layout tool or the XML design? If so, could you send your XML layout contents that are inside of activity_fun_facts.xml?

Hafeez Khan
Hafeez Khan
1,270 Points
Hafeez Khan
Hafeez Khan
1,270 Points

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".FunFactsActivity" android:background="#ff56e07e">

<TextView
    android:text="Did You Know?"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="24sp"
    android:textColor="#80ffffff"
    android:id="@+id/"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<Button
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Show Another Fun Fact"
    android:id="@+id/showFactButton"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:background="@android:color/white"
    android:textColor="@android:color/background_dark" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="The fastest slapshot on record is Bobby Hull's, which registered one hundred and eighteen miles per hour, almost 10 miles faster the Chara"
    android:id="@+id/factTextView"
    android:layout_centerVertical="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:textSize="24sp"
    android:textColor="@android:color/white" />

</RelativeLayout>

Everything above is my activity_fun_facts.xml

2 Answers

justindennison
justindennison
15,922 Points 
public class FunFactsActivity extends Activity {

private FactBook mFactBook = new FactBook();

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fun_facts);

    // Declare our View Variables and assign the Views from the layout file
    final TextView factLabel = (TextView) findViewById(R.id.factTextView);
    Button showFactButton = (Button) findViewById**(R.id.ShowFactButton)**;
    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
                 String fact = mFactBook.getFact();

            //Update the label with our dynamic fact
            factLabel.setText(fact);

        }
    };
    showFactButton.setOnClickListener(listener);

}
}

Take a look at the bolded section of your Java code. Notice that you have

android:id="@+id/showFactButton"

which shows that you have an id that is lower CamelCase but in your java code uses the capital version. Fixing that may help out.

karis hutcheson
karis hutcheson
7,036 Points
karis hutcheson
karis hutcheson
7,036 Points

I'm guessing from the error that you're missing an import declaration. If you look at your code in the IDE (assuming you're using Android Studio), click on "R" and press alt+return, it should give you a solution or the option to import the correct class.