How to add an integer variable with radio buttons in Android Studio? - android-studio

Question

I am new in using android studio, I'm having trouble on how to add an integer variable with radio buttons. First I have to get the text of the radio button and put them in an if else statement for a condition then I'll use a basic arithmetic operator. But I always get the problem of "Not a statement" whenever I declare the variable inside the if else.
Here is XML code:
<RadioGroup
android:id="#+id/radioGroup2"
android:layout_width="197dp"
android:layout_height="241dp"
android:layout_marginStart="119dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="100dp"
android:layout_marginBottom="10dp" />
<RadioButton
android:id="#+id/stronglyDisagree"
android:tag="Strongly Disagree"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:buttonTint="#000000"
android:minHeight="48dp"
android:textSize="18sp"
android:text="Strongly Disagree"
android:textColor="#color/black"
android:textStyle="bold" />
<RadioButton
android:id="#+id/disagree"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:buttonTint="#000000"
android:minHeight="48dp"
android:text="Disagree"
android:textSize="18sp"
android:textColor="#color/black"
android:textStyle="bold" />
<RadioButton
android:id="#+id/neutral"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:buttonTint="#000000"
android:minHeight="48dp"
android:text="Neutral"
android:textSize="18sp"
android:textColor="#color/black"
android:textStyle="bold" />
<RadioButton
android:id="#+id/agree"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:buttonTint="#000000"
android:minHeight="48dp"
android:textSize="18sp"
android:text="Agree"
android:textColor="#color/black"
android:textStyle="bold" />
<RadioButton
android:id="#+id/stronglyAgree"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:buttonTint="#000000"
android:minHeight="48dp"
android:textSize="18sp"
android:text="Strongly Agree"
android:textColor="#color/black"
android:textStyle="bold" />
Here is the java code:
// Intelligence Integer Data (Linguistics)
int linguistics = 0;
next.setOnClickListener(view -> {
// RadioGroup Function (Selected Radio Button)
String radiovalue ((RadioButton)this.findViewById(likert.getCheckedRadioButtonId())).getText().toString();
if(radiovalue.equals("Strongly Disagree")){
linguistics + 1;
}else if(radiovalue.equals("Disagree")){
linguistics + 2;
}else if(radiovalue.equals("Neutral")){
linguistics + 3;
}else if(radiovalue.equals("Agree")){
linguistics + 4;
}else if(radiovalue.equals("Strongly Agree")){
linguistics + 5;
}
// next question
NextQuestion(random.nextInt(questionLength)); });
I expected the integer variable I've declared will change its value and add up on each click of the submit button after selecting a radio button.