Question

我正在使用一个工作正常的自定义LayoutManager for RecyclerView（FlowLayoutManager），这是用于布置子项的函数：

@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)
{

    detachAndScrapAttachedViews(recycler);

    final int count = this.getItemCount();
    views.clear();
    lines.clear();
    for (int i = 0; i < count; i++) {
        View child = recycler.getViewForPosition(i);
        addView(child);
        measureChildWithMargins(child, 0, 0);

        final LayoutParams lp = (LayoutParams) child.getLayoutParams();

        ViewDefinition view = new ViewDefinition(this.config, child);
        view.setWidth(child.getMeasuredWidth());
        view.setHeight(child.getMeasuredHeight());
        view.setNewLine(lp.isNewLine());
        view.setGravity(lp.getGravity());
        view.setWeight(lp.getWeight());
        view.setMargins(lp.leftMargin, lp.topMargin, lp.rightMargin, lp.bottomMargin);
        views.add(view);
    }


    this.config.setMaxWidth(this.getWidth() - this.getPaddingRight() - this.getPaddingLeft());
    this.config.setMaxHeight(this.getHeight() - this.getPaddingTop() - this.getPaddingBottom());
    this.config.setWidthMode(View.MeasureSpec.EXACTLY);
    this.config.setHeightMode(View.MeasureSpec.EXACTLY);
    this.config.setCheckCanFit(true);


    CommonLogic.fillLines(views, lines, config);
    CommonLogic.calculateLinesAndChildPosition(lines);


    int contentLength = 0;
    final int linesCount = lines.size();
    for (int i = 0; i < linesCount; i++) {
        LineDefinition l = lines.get(i);
        contentLength = Math.max(contentLength, l.getLineLength());
    }


    LineDefinition currentLine = lines.get(lines.size() - 1);
    int contentThickness = currentLine.getLineStartThickness() + currentLine.getLineThickness();
    int realControlLength = CommonLogic.findSize(this.config.getLengthMode(), this.config.getMaxLength(), contentLength);
    int realControlThickness = CommonLogic.findSize(this.config.getThicknessMode(), this.config.getMaxThickness(), contentThickness);


    CommonLogic.applyGravityToLines(lines, realControlLength, realControlThickness, config);


    for (int i = 0; i < linesCount; i++) {
        LineDefinition line = lines.get(i);
        applyPositionsToViews(line);
    }
}

唯一的问题是，当我调用notifyDataSetChanges（）或notifyItemChanges（）时，它再次调用onLayoutChildren（），整个recyclerview正在更改内容，并且它会向右滚动回到顶部。

我试着看看LinearLayoutManager如何控制这个问题但是我无法理解。

如何将RecyclerView保持在当前状态但仅更改内容？或者我如何滚动到相同的位置？

Answer 1

如果您要更新特定项目或项目范围，请使用notifyItemChanged(position)或notifyItemRangeChanged(startpos, endpos)。还有插入方法（notifyItemInserted(pos)）和删除（notifyItemRemoved(pos)）

RecyclerView重绘onLayoutChildren（）上的内容

1 个答案: