How can I change the buttonTint form a radioButton if it's selected?

The user can chosse between 4 different radioButtons and each of them will set a different enum.

At the beginning I just put them in a radioGroup in my layout and I figured out that the standart color of the circle and dot from the radioButtons (black) are "hiding" caused by the darkblue background. I tried a bit and figured out that buttonTint is the right property to change the color of the circle/dot from the radioButtons.

Now I'm trying to code an if-statement (in an if statement, see code below) which causes the change of the circle's /dot's color from the radioButton if it's selected. This should happen before I "activate" the checking method/button.

I tried a bit and all I learned were 5 different ways how it's not changing the color.

I will mark the method which isn't working/missing with XXXX.

Java code:

public void setKnowledge() {
    setContentView(R.layout.knowledge_level);

    Button checking = (Button) findViewById(R.id.buttonChecking);

    checking.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            checkSelection();
            categoryAuswahl();
        }
    });
}

public knowledge checkSelection() {
    RadioButton rbNoob = (RadioButton) findViewById(R.id.radioButtonNoob);
    RadioButton rbBeginner = (RadioButton) findViewById(R.id.radioButtonBeginner);
    RadioButton rbAdvanced = (RadioButton) findViewById(R.id.radioButtonAdv);
    RadioButton rbPro = (RadioButton) findViewById(R.id.radioButtonPro);
    RadioButton rbGrandMaster = (RadioButton) findViewById(R.id.radioButtonGM);

    if(rbNoob.isChecked()) {
        if(rbNoob.XXXX()) {
            rbNoob.setButtonTintList(ColorStateList.valueOf(Color.parseColor("#511613")));
        } else {
            rbNoob.setBackgroundTintList(ColorStateList.valueOf(Color.parseColor("#E0E0E0")));
        }
        return knowledge.NOOB;
    }
    else if(rbBeginner.isChecked()) {
        return knowledge.BEGINNER;
    }
    else if(rbAdvanced.isChecked()) {
        return knowledge.ADVANCED;
    }
    else if(rbPro.isChecked()) {
        return knowledge.PRO;
    }
    else if(rbGrandMaster.isChecked()) {
        return knowledge.GM;
    }
    return null;
}

As XXXX I tried "isSelected();", "isPressed();", "isEnabled();", "isActivated();" and "isChecked();" but everthing didn't work.

The color should change in the moment the user presses on the radioButton, so in "realtime".

My XML (if neded) [knowledge_level.xml]

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://ift.tt/nIICcg"
xmlns:app="http://ift.tt/GEGVYd"
xmlns:tools="http://ift.tt/LrGmb4"
android:id="@+id/layoutTestwissenstand"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#081929">

<RadioGroup
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="32dp"
    app:layout_constraintTop_toBottomOf="@+id/testWissenstandText"
    android:layout_marginLeft="8dp"
    app:layout_constraintLeft_toLeftOf="parent"
    android:id="@+id/radioGroup"
    app:layout_constraintRight_toLeftOf="@+id/buttonChecking"
    android:layout_marginRight="8dp"
    app:layout_constraintHorizontal_bias="0.538">

    <RadioButton
        android:id="@+id/radioButtonNoob"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="8dp"
        android:checked="true"
        android:text="Keine Vorkenntnisse"
        android:textAlignment="center"
        android:textColor="#E0E0E0"
        android:textSize="18sp"
        android:textStyle="bold"
        app:buttonTint="#E0E0E0"
        app:layout_constraintHorizontal_bias="0.505"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/buttonChecking"
        app:layout_constraintTop_toBottomOf="@+id/testWissenstandText"/>

    <RadioButton
        android:id="@+id/radioButtonBeginner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="8dp"
        android:checked="true"
        android:text="Anfänger"
        android:textAlignment="center"
        android:textColor="#E0E0E0"
        android:textSize="18sp"
        android:textStyle="bold"
        app:buttonTint="#E0E0E0"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintLeft_toLeftOf="@+id/radioButtonNoob"
        app:layout_constraintRight_toRightOf="@+id/radioButtonNoob"
        app:layout_constraintTop_toBottomOf="@+id/radioButtonNoob"/>

    <RadioButton
        android:id="@+id/radioButtonAdv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="8dp"
        android:text="Fortgeschrittener"
        android:textAlignment="center"
        android:textColor="#E0E0E0"
        android:textSize="18sp"
        android:textStyle="bold"
        app:buttonTint="#E0E0E0"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintLeft_toLeftOf="@+id/radioButtonBeginner"
        app:layout_constraintRight_toRightOf="@+id/radioButtonBeginner"
        app:layout_constraintTop_toBottomOf="@+id/radioButtonBeginner"/>

    <RadioButton
        android:id="@+id/radioButtonPro"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="8dp"
        android:text="Pro"
        android:textAlignment="center"
        android:textColor="#E0E0E0"
        android:textSize="18sp"
        android:textStyle="bold"
        app:buttonTint="#E0E0E0"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintLeft_toLeftOf="@+id/radioButtonAdv"
        app:layout_constraintRight_toRightOf="@+id/radioButtonAdv"
        app:layout_constraintTop_toBottomOf="@+id/radioButtonAdv"/>

    <RadioButton
        android:id="@+id/radioButtonGM"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="8dp"
        android:text='"Grand Master"'
        android:textAlignment="center"
        android:textColor="#E0E0E0"
        android:textSize="18sp"
        android:textStyle="bold"
        app:buttonTint="#E0E0E0"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintLeft_toLeftOf="@+id/radioButtonPro"
        app:layout_constraintRight_toRightOf="@+id/radioButtonPro"
        app:layout_constraintTop_toBottomOf="@+id/radioButtonPro"/>

</RadioGroup>

<ImageView
    android:id="@+id/kastenKnowledge"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="16dp"
    app:layout_constraintHorizontal_bias="0.517"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:srcCompat="@drawable/kasten"/>

<TextView
    android:id="@+id/testWissenstandHeader"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    android:text="Dein Wissensstand?"
    android:textAlignment="center"
    android:textColor="#511613"
    android:textSize="32sp"
    android:textStyle="bold"
    app:layout_constraintBottom_toBottomOf="@+id/kastenKnowledge"
    app:layout_constraintLeft_toLeftOf="@+id/kastenKnowledge"
    app:layout_constraintRight_toRightOf="@+id/kastenKnowledge"
    app:layout_constraintTop_toTopOf="@+id/kastenKnowledge"/>

<TextView
    android:id="@+id/testWissenstandText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginEnd="16dp"
    android:layout_marginStart="16dp"
    android:layout_marginTop="24dp"
    android:text='Wie würdest du deinen Wissenstand\nbezüglich dem Spieleinhalt\nvon "Overwatch" beurteilen?'
    android:textAlignment="center"
    android:textColor="#E0E0E0"
    android:textSize="20sp"
    app:layout_constraintHorizontal_bias="0.512"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/testWissenstandHeader"/>

<Button
    android:id="@+id/buttonChecking"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_marginEnd="16dp"
    android:layout_marginStart="0dp"
    android:background="@drawable/button_box"
    android:text="C\nL\nI\nC\nK"
    android:textAllCaps="false"
    android:textColor="#511613"
    android:textSize="16sp"
    android:textStyle="bold"
    app:layout_constraintRight_toRightOf="parent"
    android:layout_marginRight="16dp"
    app:layout_constraintBottom_toBottomOf="@+id/radioGroup"
    android:layout_marginBottom="8dp"
    app:layout_constraintTop_toTopOf="@+id/radioGroup"
    android:layout_marginTop="8dp"
    app:layout_constraintVertical_bias="0.5"/>



<TextView
    android:id="@+id/knowledgeHint"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="0dp"
    android:layout_marginRight="0dp"
    android:text="Wenn du einen Wissenstand\nfestgelegt hast, drücke den\nKnopf daneben!"
    android:textAlignment="center"
    android:textColor="#FF4400"
    android:textSize="20sp"
    android:textStyle="bold|italic"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    android:layout_marginTop="32dp"
    app:layout_constraintTop_toBottomOf="@+id/radioGroup"/>

</android.support.constraint.ConstraintLayout>

The code should be written in java and jQuery/javascript (or c#) should be avoided if possible.