Create multiple ArrayLists, return-function

Question

I´ve made 3 ArrayLists with objects of the type <ObjektsDEGR>.

ObjektsDEGR class:

public class ObjektsDEGR implements Serializable {

    private String voc;
    private String vocTR;
    private int index;
    private int box;

    private transient String vocF1;
    private transient String vocF2;
    private transient String vocF3;
    private transient String vocF4;
    private transient String vocF5;

    //+++++++++++ KONSTRUKTOR +++++++++++++

    public ObjektsDEGR(int voc, int vocTR, int index, int box, int vocF1, int vocF2, int vocF3, int vocF4, int vocF5){

        this.voc = Integer.toString(voc);
        this.vocTR = Integer.toString(vocTR);
        this.index = index;
        this.vocF1 = Integer.toString(vocF1);
        this.vocF2 = Integer.toString(vocF2);
        this.vocF3 = Integer.toString(vocF3);
        this.vocF4 = Integer.toString(vocF4);
        this.vocF5 = Integer.toString(vocF5);
        this.box = box;
    }

    //+++++ GETTER ++++++

    public int getIndex(){
        return index;
    }
    public String getVoc() {
        return voc;
    }
    public String getVocTR(){
        return vocTR;
    }
    public String getVocF1() {
        return vocF1;
    }
    public String getVocF2() {
        return vocF2;
    }
    public String getVocF3() {
        return vocF3;
    }
    public String getVocF4() {
        return vocF4;
    }
    public String getVocF5() {
        return vocF5;
    }
    public int getBox(){
        return box;
    }

    //++++ SETTER +++++

    public void setIndex(int index){
        this.index = index;
    }
    public void setVoc(int voc){
        this.voc = Integer.toString(voc);
    }
    public void setVocTR(int vocTR){
        this.vocTR = Integer.toString(vocTR);
    }
    public void setVocF1(int vocF1){
        this.voc = Integer.toString(vocF1);
    }
    public void setVocF2(int vocF2){
        this.voc = Integer.toString(vocF2);
    }
    public void setVocF3(int vocF3){
        this.voc = Integer.toString(vocF3);
    }
    public void setVocF4(int vocF4){
        this.voc = Integer.toString(vocF4);
    }
    public void setVocF5(int vocF5){
        this.voc = Integer.toString(vocF5);
    }
    public void setBox (int box){ this.box = box;}
}

These Objekts i´ve divided into 3 ArrayLists, depending on the value of the "box" attribute.

How can i get the ArrayList "outputList" from outside of the method?

ObjektsDEGR[] basicDEGR = new ObjektsDEGR[allVoc];

public ArrayList<ObjektsDEGR> writeToArrayList(int category) {

        ArrayList<ObjektsDEGR> box1Filtered = new ArrayList<>();
        ArrayList<ObjektsDEGR> box2Filtered = new ArrayList<>();
        ArrayList<ObjektsDEGR> box3Filtered = new ArrayList<>();
        ArrayList<ObjektsDEGR> outputList = new ArrayList<>();

        Integer comparer1 = 1;
        Integer comparer2 = 2;
        Integer comparer3 = 3;

        //region Implementierung
        for (int j = ((category-1)*nV); j < nV+((category-1)*nV); j++){

        if (comparer1.equals(basicDEGR[j].getBox())) {
            box1Filtered.add(basicDEGR[j]);
        }
            else if (comparer2.equals(basicDEGR[j].getBox())) {
                box2Filtered.add(basicDEGR[j]);
            }
            else if (comparer3.equals(basicDEGR[j].getBox())) {
                box3Filtered.add(basicDEGR[j]);
            }
            else {
                box3Filtered.add(basicDEGR[j]);
            }
            }//endregion


    if (box1Filtered.isEmpty())
    {
        if (box2Filtered.isEmpty()) {
            outputList = box3Filtered;
        }
        else {
            outputList = box2Filtered;
        }
    }
    else
    {
        outputList = box1Filtered;
    }

    public ArrayList<ObjektsDEGR> getOutputList(){
        return outputList;
    }
        }

jnrdn0011 · Accepted Answer · 2021-02-18 00:36:40Z

If you want to just return only outputList

public ArrayList<ObjektsDEGR> writeToArrayList(int category) {
    ArrayList<ObjektsDEGR> box1Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> box2Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> box3Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> outputList = new ArrayList<>();

    /*
     * your main logic
     *
     * */

    return outputList;
}

If you want to return all lists You can return List of ArrayList

public List<ArrayList<ObjektsDEGR>> writeToArrayList(int category) {
    ArrayList<ObjektsDEGR> box1Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> box2Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> box3Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> outputList = new ArrayList<>();

    /*
     * your main logic
     *
     * */

    List<ArrayList<ObjektsDEGR>> resultList = new ArrayList<>();
    resultList.add(box1Filtered);
    resultList.add(box2Filtered);
    resultList.add(box3Filtered);
    resultList.add(outputList);
    return resultList;
}

Or List of array if you have fixed number of data to return

public ArrayList<ObjektsDEGR>[] writeToArrayList(int category) {
    ArrayList<ObjektsDEGR> box1Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> box2Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> box3Filtered = new ArrayList<>();
    ArrayList<ObjektsDEGR> outputList = new ArrayList<>();

    /*
     * your main logic
     *
     * */

    return (ArrayList<ObjektsDEGR>[]) new ArrayList[]{box1Filtered, box2Filtered, box3Filtered, outputList};
}

Tokazio · Accepted Answer · 2021-02-18 00:35:26Z

1

You can't put a method in another method.

You can just return outputList from writeToArrayList

Or

In writeToArrayList use

Return instead of outputList =

You doesn't need the outputList variable anymore You must return in each cases, with an empty list at the end for example Remove

        return outputList;
    }

edited Feb 18, 2021 at 0:35

answered Feb 18, 2021 at 0:30

Tokazio

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