我要一个片段添加到编程方式实现其布局的活动。我查了一下片段文件，但不会有太多的例子说明我需要什么。这里是code我试着写的类型：

I want to add a Fragment to an Activity that implements its layout programmatically. I looked over the Fragment documentation but there aren't many examples describing what I need. Here is the type of code I tried to write:

public class DebugExampleTwo extends Activity {

    private ExampleTwoFragment mFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        FrameLayout frame = new FrameLayout(this);
        if (savedInstanceState == null) {
            mFragment = new ExampleTwoFragment();
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.add(frame.getId(), mFragment).commit();
        }

        setContentView(frame);
    }
}

...

public class ExampleTwoFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, 
                             ViewGroup container, 
                             Bundle savedInstanceState) {
        Button button = new Button(getActivity());
        button.setText("Hello There");
        return button;
    }
}

这code编译但崩溃的开始，可能是因为我的 FragmentTransaction.add（）不正确。什么是做到这一点的正确方法？

This code compiles but crashes at start, probably because my FragmentTransaction.add() is incorrect. What is the correct way to do this?

推荐答案

原来有一个以上的问题，即code。片段不能声明的方式，同样的Java文件的活动，但不是作为一个公共内部类中。该框架预计片段的构造函数（不带参数）是公开可见。移动片段插入到活动作为一个内部类，或创建一个新的Java文件碎片修复。

It turns out there's more than one problem with that code. A fragment cannot be declared that way, inside the same java file as the activity but not as a public inner class. The framework expects the fragment's constructor (with no parameters) to be public and visible. Moving the fragment into the Activity as an inner class, or creating a new java file for the fragment fixes that.

第二个问题是，当你加入一个片段这样，你必须通过引用片段的含视图，该视图必须有一个自定义的ID。使用默认的ID会崩溃的应用程序。下面是更新code：

The second issue is that when you're adding a fragment this way, you must pass a reference to the fragment's containing view, and that view must have a custom id. Using the default id will crash the app. Here's the updated code:

public class DebugExampleTwo extends Activity {

    private static final int CONTENT_VIEW_ID = 10101010;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        FrameLayout frame = new FrameLayout(this);
        frame.setId(CONTENT_VIEW_ID);
        setContentView(frame, new LayoutParams(
            LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));

        if (savedInstanceState == null) {
            Fragment newFragment = new DebugExampleTwoFragment();
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.add(CONTENT_VIEW_ID, newFragment).commit();
        }
    }

    public static class DebugExampleTwoFragment extends Fragment {
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            EditText v = new EditText(getActivity());
            v.setText("Hello Fragment!");
            return v;
        }
    }
}