AlertDialog ,Checkbox have a line between each other

i have a alertdialog and style is Checkbox, I need to plus a line between each other. Because i have too much item. thanks for help.

this is my code

public Button.OnClickListener IMBL = new Button.OnClickListener() {
    public void onClick(View v) {
        AfterClick = new boolean[items.length];
        for (int i = 0; i < AfterClick.length; i++) {
            AfterClick[i] = false;
        }

        AlertDialog dialog = new AlertDialog.Builder(Daycarddd.this)
                .setTitle("skill")
                .setMultiChoiceItems(items, AfterClick,
                        new DialogInterface.OnMultiChoiceClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int indexSelected, boolean isChecked) {
                                if (isChecked) {

                                    for (int i = 0; i < AfterClick.length; i++) {
                                        if (AfterClick[i]) {
                                        }

                                    }
                                } else if (seletedItems
                                        .contains(indexSelected)) {
                                    // Else, if the item is already in the
                                    // array, remove it
                                    seletedItems.remove(Integer
                                            .valueOf(indexSelected));
                                }
                            }
                        })
                .setPositiveButton("confirm",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int id) {

                                for(int j=0;j< items.length;j++){                                           
                                    if(AfterClick[j]==true){            

                                    if(resultcheck==""){resultcheck=items[j];}else
                                      resultcheck =resultcheck+","+items[j] ;
                                    }
                                  } 
                                checkbox=resultcheck;
                                resultcheck="";
                                Toast.makeText(Daycarddd.this,
                                        checkbox,
                                        Toast.LENGTH_SHORT).show();
                            }
                        })
                .setNegativeButton("cancle",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int id) {
                            }
                        }).create();
        dialog.show();
    }
};