安卓：使用片断编程 [英] Android: using fragments programmatically

问题描述

对于一些原因，我不能使用XML布局文件。

For some reasons I can't use xml layout files.

不过，我需要创建一个平板电脑的Andr​​oid应用程序。

But I need to create a tablet android app.

我决定采用碎片。

我想创建相同的布局，这个XML生成：

I want to create the same layout that this xml generates:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent" android:layout_height="fill_parent">

    <fragment class="com.example.ItemsList"
            android:id="@+id/items_list" android:layout_weight="1"
            android:layout_width="0dp" android:layout_height="fill_parent" />

    <FrameLayout android:id="@+id/item_details" android:layout_weight="1"
            android:layout_width="0dp" android:layout_height="fill_parent"
            android:background="?android:attr/detailsElementBackground" />

</LinearLayout>

不过，我有问题的片段添加到我的LinearLayout：

But I have problems with adding fragments to my linearLayout:

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(createUI());
    }

    private View createUI() {
        LinearLayout layout = new LinearLayout(this);

        layout.setOrientation(LinearLayout.HORIZONTAL);
        layout.setLayoutParams(new LinearLayout.LayoutParams(AbsListView.LayoutParams.FILL_PARENT, AbsListView.LayoutParams.FILL_PARENT));
        layout.setId(0x101);
        {
            FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
            fragmentTransaction.add(0x101, new ItemsList());
            fragmentTransaction.add(0x101, new ItemDetails());
            fragmentTransaction.commit();
        }
        return layout;
    }

事实上，我甚至不能创建的LinearLayout有两个相同的片段：

Actually I can't even create LinearLayout with two identical fragments:

            ...
            fragmentTransaction.add(0x101, new ItemsList());
            fragmentTransaction.add(0x101, new ItemsList());
            ...

请帮忙

顺便说一句我想不出为什么我们需要声明的FrameLayout为itemDetails片段，但片段是够itemsList ListFragment？

Btw I can't figure out why do we need to declare "FrameLayout" for itemDetails Fragment but "fragment" is enough for itemsList ListFragment?

UPD：

要做到这一点应该只需添加第三个参数：

To do so one should just add third param:

            ...
            fragmentTransaction.add(0x101, new ItemsList(), "uniqueTag1");
            fragmentTransaction.add(0x101, new ItemsList(), "uniqueTag2");
            ...

对于变量参数的默认值是空的，所以我试图创建具有相同的ID两个不同的元素。由于P-LO为他的评论。

Default value for the tag parameter is null, so I was trying to create two different elements with identical ids. Thanks to p-lo for his comment.

推荐答案

我已经找到了解决方案。

I've found the solution.

（更好的方式加入到这个问题。谢谢，P-LO）

(the better way was added to the question. Thanks, p-lo)

如果您希望将多个片段上的活动，你应该创建布局每个片段：

If you want to place more than one fragment on activity you should create layouts for each fragment:

    private View createUI() {
        LinearLayout layout = new LinearLayout(this);

        layout.setOrientation(LinearLayout.HORIZONTAL);
        layout.setLayoutParams(new LinearLayout.LayoutParams(AbsListView.LayoutParams.FILL_PARENT, AbsListView.LayoutParams.FILL_PARENT));


        LinearLayout innerLayout1 = new LinearLayout(this);
        innerLayout1.setLayoutParams(new LinearLayout.LayoutParams(300, ViewGroup.LayoutParams.FILL_PARENT));
        innerLayout1.setId(ITEMS_LIST_ID);
        {
            FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
            fragmentTransaction.add(ITEMS_LIST_ID, new ItemsList());
            fragmentTransaction.commit();
        }
        layout.addView(innerLayout1);

        LinearLayout innerLayout2 = new LinearLayout(this);
        innerLayout2.setLayoutParams(new LinearLayout.LayoutParams(300, ViewGroup.LayoutParams.FILL_PARENT));
        innerLayout2.setId(ITEM_DETAILS_ID);
        {
            FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
            fragmentTransaction.add(ITEM_DETAILS_ID, new ItemDetails());
            fragmentTransaction.commit();
        }
        layout.addView(innerLayout2);

        return layout;


    }

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