Android：无法接收BottomSheetDialog状态更改回调

Question

我已经像这样实现了BottomSheetDialog：

addLinkSheet = new BottomSheetDialog(this);
addLinkSheetView = getLayoutInflater().inflate(R.layout.dialog_quickadd_wagrouplink, null);
addLinkSheet.setContentView(addLinkSheetView);
addLinkSheet.show();

我正在尝试使用以下代码来听取底部工作表（Expanded / Collapsed / Hidden）的状态更改：

BottomSheetBehavior behavior = BottomSheetBehavior.from((View)addLinkSheetView.getParent());
    behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
        @Override
        public void onStateChanged(@NonNull View bottomSheet, int newState) {
            Toast.makeText(QuickAddWaGroup.this, "State changed", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onSlide(@NonNull View bottomSheet, float slideOffset) {

        }
    });

我的BottomSheet显示正常，但我从来没有看到状态的Toast被改变。我做错了吗？

Answer 1

你必须将Callback包装在BottomSheetDialog的OnShowListener中，它应该工作：

bottomSheetDialog = new BottomSheetDialog(this);
View contentView = getLayoutInflater().inflate(R.layout.bottom_content_view, null);
bottomSheetDialog.setContentView(contentView);
bottomSheetDialog.setCancelable(true);
bottomSheetDialog.setOnShowListener(new DialogInterface.OnShowListener() {
    @Override
    public void onShow(DialogInterface dialogInterface) {
        bottomSheetBehavior = BottomSheetBehavior.from((View)contentView.getParent());
        bottomSheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
            @Override
            public void onStateChanged(@NonNull View bottomSheet, int newState) {
                if (newState == BottomSheetBehavior.STATE_EXPANDED) {
                    Log.d(TAG, "State Expanded");
                    // ... do whatever is required on 'expanded'
                } else if (newState == BottomSheetBehavior.STATE_HIDDEN) {
                    bottomSheetDialog.dismiss();
                }
            }

            @Override
            public void onSlide(@NonNull View bottomSheet, float slideOffset) {
                if (bottomSheetBehavior.getState() == BottomSheetBehavior.STATE_EXPANDED) {
                    if (Math.abs(slideOffset) > 0) {
                        bottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
                        bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);
                    }
                }
            }
        });

        bottomSheetBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
    }
});

// Get your contentView children set here...
bottomSheetDialog.show();

关闭bottomSheetdialog;你会需要：

bottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
bottomSheetBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);

这将再次触发onStateChanged事件并关闭对话框。

Answer 2

我最初试图在Fragment中覆盖onCreateView方法来设置布局，但是没有通知Bottom Sheet状态更改。只有在我覆盖了BottomSheetDialogFragment中的setupDialog方法而不是onCreateView之后，才能听到状态更改。这是示例代码

public class AddMetricFragment extends BottomSheetDialogFragment {

BottomSheetBehavior.BottomSheetCallback bottomSheetCallback = new BottomSheetBehavior.BottomSheetCallback() {
    @Override
    public void onStateChanged(@NonNull View bottomSheet, int newState) {
        // React to state change
            Log.d("logtag", "Bottom Sheet State " + newState);
    }

    @Override
    public void onSlide(@NonNull View bottomSheet, float slideOffset) {
        // React to dragging events

    }
};

@Override
public void setupDialog(Dialog dialog, int style) {
    super.setupDialog(dialog, style);

    contentView = View.inflate(getContext(), R.layout.bottom_sheet_layout, null);
    dialog.setContentView(contentView);
    CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) ((View) contentView.getParent()).getLayoutParams();
    CoordinatorLayout.Behavior behavior = layoutParams.getBehavior();
    if (behavior != null && behavior instanceof BottomSheetBehavior) {
        ((BottomSheetBehavior) behavior).setBottomSheetCallback(bottomSheetCallback);
    }
}

}