myactivity代码如下：

public class MyActivity extends AppCompatActivity {        @Override        protected void onCreate(@Nullable Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            setContentView(R.layout.activity_my);            new MyBottomSheetFragment().show(getSupportFragmentManager(), "tag");        }        public static class MyBottomSheetFragment extends BottomSheetDialogFragment {            @Override            public Dialog onCreateDialog(Bundle savedInstanceState) {                BottomSheetDialog bottomSheetDialog = (BottomSheetDialog) super.onCreateDialog(savedInstanceState);                bottomSheetDialog.setContentView(R.layout.sample);                try {                    Field mBehaviorField = bottomSheetDialog.getClass().getDeclaredField("mBehavior");                    mBehaviorField.setAccessible(true);                    final BottomSheetBehavior behavior = (BottomSheetBehavior) mBehaviorField.get(bottomSheetDialog);                    behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {                        @Override                        public void onStateChanged(@NonNull View bottomSheet, int newState) {                            if (newState == BottomSheetBehavior.STATE_DRAGGING) {                                behavior.setState(BottomSheetBehavior.STATE_EXPANDED);                            }                        }                        @Override                        public void onSlide(@NonNull View bottomSheet, float slideOffset) {                        }                    });                } catch (NoSuchFieldException e) {                    e.printStackTrace();                } catch (IllegalAccessException e) {                    e.printStackTrace();                }                return bottomSheetDialog;            }        }    }

这个地方的r.layout.sample是一个简单的布局：

你会得到下面的输出：

原文地址：