android9.1

### oefening 1 ###

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".aView">

    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <EditText
                android:id="@+id/inputGetal1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:inputType="number"
                android:hint="geef geheel getal"/>

            <TextView
                android:id="@+id/tvLijstCijfers"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <Button
                android:id="@+id/btnAdd"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Berekenen"
                android:onClick="onRefresh"/>

            <TextView
                android:id="@+id/tvGemCijfers"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

        </TableRow>

    </TableLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

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### oefening 2 ###

public class aView extends AppCompatActivity {

    aModel aModel1 = new aModel();
    aController controller1 = new aController(aModel1);

    ...

    public void onRefresh(View view) {
        EditText etInputGetal = (EditText)findViewById(R.id.inputGetal1);
        int getal = Integer.valueOf(etInputGetal.getText().toString());
        controller1.addToLijst(aModel1,getal);

        TextView tvLijstCijfers = (TextView)findViewById(R.id.tvLijstCijfers);
        TextView tvGemCijfers = (TextView)findViewById(R.id.tvGemCijfers);

        String strLijst = TextUtils.join(",", aModel1.getLijst());
        String strGemid = String.valueOf(aModel1.getGemiddelde());

        tvLijstCijfers.setText(strLijst);
        tvGemCijfers.setText(strGemid);
    }

    ...
    
}

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### oefening 3 ###

public class aModel {

    ArrayList<Integer> cijferList = new ArrayList<>();

    public aModel() {

    }

    public void addToLijst(int newNumber) {
        cijferList.add(newNumber);
    }

    public ArrayList getLijst() {
        return cijferList;
    }

    public double getGemiddelde() {
        double gemidDouble = calcGemiddelde(cijferList);
        return gemidDouble;
    }

    private double calcGemiddelde(ArrayList<Integer> numberList) {
        Integer sum = 0;
        if (!numberList.isEmpty()) {
            for (Integer numList: numberList) {
                sum = sum + numList;
            }
        }
        return sum.doubleValue() / numberList.size();
    }
}

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### oefening 4 ###

public class aController {

    aController(aModel aModel) {
    }

    public void addToLijst(aModel aModel2, int newGetal) {
        aModel2.addToLijst(newGetal);
    }
}

Download hier het bestand.