为主从视图片段创建“下一个”和“上一个”方法的类

Question

I wanted to create a class that holds my previous and next button. The class will help to reduce the number of repeating codes that I had to write for each button in each class. For example, the following code is called inside FirstPage.class fragment.

PageTransition.pageContents(CaseContent.getSize(), getArguments().getString(ARG_ITEM_ID), button_next, button_prev);

The next and previous buttons are stored in the header.xml which I've called in each layout. I used a master-detail view for my codes.

I tried to use the same code in CaseListActivity for my class. However, I have problem with getSupportFragmentManager when I tried to add the codes to nextPage() method inside PageTransition .

Bundle arguments = new Bundle(); Fragment fragment; arguments.putString(FirstPage.ARG_ITEM_ID, id); fragment = new FirstPage(); fragment.setArguments(arguments); getSupportFragmentManager().beginTransaction()
.replace(R.id.case_detail_container, fragment) .commit();

Is there a better way to construct my transition class?

CaseListActivity.java

public class CaseListActivity extends AppCompatActivity {

    ....

    //Method:- direct user to selected Item page

        void onSelectedMenuItem(String id, View v) {

            Bundle arguments = new Bundle();
            Fragment fragment;

            //in landscape
            switch (id) {
                case "1":
                    arguments.putString(FirstPage.ARG_ITEM_ID, id);
                    fragment = new FirstPage();
                    break;

                ... // case continues untill 12

                    break;
                case "11":
                    arguments.putString(ElevethPage.ARG_ITEM_ID, id);
                    fragment = new ElevethPage();

                    break;
                case "12":
                    arguments.putString(LastPage.ARG_ITEM_ID, id);
                    fragment = new LastPage();

                    break;
                default:
                    arguments.putString(FirstPage.ARG_ITEM_ID, id);
                    fragment = new FirstPage();
                    break;
            }

            fragment.setArguments(arguments);
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.case_detail_container, fragment)
                    .commit();

            //in potrait
            if (onePane) {

                //hide recyclerview list and show containerview
                final DisplayMetrics displayMetrics = new DisplayMetrics();
                getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);

                assert recyclerView != null;
                final ViewGroup.LayoutParams paramsRecyclerView = recyclerView.getLayoutParams();
                assert containerView != null;
                final ViewGroup.LayoutParams paramsContainerView = containerView.getLayoutParams();
                paramsRecyclerView.width = 0;
                paramsContainerView.width = displayMetrics.widthPixels;
                recyclerView.setLayoutParams(paramsRecyclerView);
                containerView.setLayoutParams(paramsContainerView);

                //show expand recylcerview list button
                ActionButton.setVisibility(View.VISIBLE);

            }
        }

        ....
    }

FirstPage.java

public class FirstPage extends Fragment {

public static final String ARG_ITEM_ID = "item_id";
...

public void onViewCreated(final View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

//      TODO: next & prev button
        TextView button_prev = (TextView) view.findViewById(R.id.btn_prev);
        TextView button_next = (TextView) view.findViewById(R.id.btn_nxt);
        PageTransition.pageContents(CaseContent.getSize(), getArguments().getString(ARG_ITEM_ID), button_next, button_prev);
        ....
    }

}

PageTransition.java

public class PageTransition {

    public static final String TAG = PageTransition.class.getSimpleName();

    //take number of pages
    public static void pageContents(int totalPage, String id, TextView next, TextView previous) {
        //change string string to int
        int pageID = Integer.parseInt(id);
        final int prevID, nextID; // id for next & prev page

        if(pageID == 1) {
            previous.setVisibility(View.GONE); //hide prev button onn 1st page

            prevID = 0;
            nextID = ++pageID;

            next.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    nextPage(nextID);
                }
            });

            Log.d(TAG, "pageContents: first page");

        } else if (pageID < totalPage - 1 && pageID !=1) {
            prevID = --pageID;
            nextID = 2+pageID;

            next.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    nextPage(nextID);
                }
            });

            previous.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    prevPage(prevID);
                }
            });


        } else if (pageID == totalPage) {
            next.setVisibility(View.GONE); //hide next button on last page

            prevID = --pageID;
            nextID = 0;

            previous.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    prevPage(prevID);
                }
            });
        }

    }

    private static void nextPage(int id) {

        Log.d(TAG, "nextPage: id " + id);

    }

    private static void prevPage(int id) {

        Log.d(TAG, "prevPage: id " + id);

    }
}

Answer 1

After some thoughts, I finally able to work it out. I've to sent the current fragment, which hold the "next" and "prev" buttons to the class. Only then, i'm able to use getFragmentManager . I use the following code inside FirstPage.java to set the "next" & "pre" buttons.

PageTransition.pageContents( this , CaseContent.getSize(), " formA ", getArguments().getString(ARG_ITEM_ID), button_next, button_prev);

Then on item list, I add this code whenever use clicked on one of the item list menu.

Fragment fragment = PageTransition.init(id, "formA"); getSupportFragmentManager().beginTransaction() .replace(R.id.case_detail_container, fragment) .commit();

PageTransition.java

public class PageTransition {

    public static final String TAG = PageTransition.class.getSimpleName();
    private static int pageId;

    public static Fragment init(String id, String form) {
        Log.d(TAG, "currentPage: id " + id);
        pageId = Integer.valueOf(id); //set current page Id

        switch(form) {
            case "formA" :
                return formA_caseContent(id);
            case "formB" :
                return formB_caseContent(id);
            case "formC" :
                return formC_caseContent(id);
            default:
                Log.d(TAG, "currentPage: form id " + form + " out of bound.");
                return null;
        }
    }

    public static void pageContents(final Fragment fragment, int totalPage, final String form, String id, TextView next,
                                    TextView previous) {
        //change string string to int
        int pageID = Integer.parseInt(id);
        int prevID = 0, nextID = 0;

        if(pageID == 1) {
            previous.setVisibility(View.GONE); //hide prev button onn 1st page
            nextID = ++pageID;

        } else if (pageID > 1 && pageID < totalPage ) {
            prevID = --pageID;
            nextID = 2+pageID;

        } else if (pageID == totalPage) {
            next.setVisibility(View.GONE); //hide next button on last page
            prevID = --pageID;

        }

        final int finalNextID = nextID;
        next.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Fragment _fragment = init(String.valueOf(finalNextID), form);
                    fragment.getFragmentManager().beginTransaction()
                            .replace(R.id.case_detail_container, _fragment).commit();
                }
            });

        final int finalPrevID = prevID;
        previous.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Fragment _fragment = init(String.valueOf(finalPrevID), form);
                    fragment.getFragmentManager().beginTransaction()
                            .replace(R.id.case_detail_container, _fragment).commit();
                }
            });

    }

    private static Fragment formA_caseContent(String id) {

        Bundle arguments = new Bundle();
        Fragment fragment;

        switch (id) {
            case "1":
                arguments.putString(FirstPage.ARG_ITEM_ID, id);
                fragment = new FirstPage();

                break;
            case"2":
                arguments.putString(SecondPage.ARG_ITEM_ID, id);
                fragment = new SecondPage();

                break;
            ....
            default:
                Log.i(TAG, "onSelectedMenuItem: Selection out of bound.");
                arguments.putString(FirstPage.ARG_ITEM_ID, id);
                fragment = new FirstPage();
                break;
        }

        fragment.setArguments(arguments);
        return fragment;
    }

    private static Fragment formB_caseContent(String id) {}

    private static Fragment formc_caseContent(String id) {}
}