為什么我的Android自定義適配器樣式隨機行？

Question

我有一個簡單的自定義適配器，用於顯示度數列表。 我正在嘗試添加一種方法來使列表中的子標題具有相似的內容。 每行都有一個標題和描述，所以我要做的是將描述設置為null的行膨脹時，它會更改行的樣式（隱藏描述並使標題居中）。 我遇到的問題是將樣式應用於隨機行，而不是僅將其應用於具有空值的樣式（隨機行的標題將居中，而其他隨機行的描述將被隱藏）我的getView：

public View getView(int position, View convertView, ViewGroup parent) {
    View v = convertView;
    if(v == null) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        v = inflater.inflate(R.layout.links_list, null);
    }

    TextView tvTitle = (TextView)v.findViewById(R.id.txtTitle);
    TextView tvDesc = (TextView)v.findViewById(R.id.txtDesc);

    if(mainList.get(position) instanceof Program) {
        Program row = (Program) mainList.get(position);
        if(row.getTitle() != null && row.getType() == null) {
            //this condition should style just the ones with null type, but style random rows instead
            tvTitle.setText(row.getTitle());
            tvTitle.setGravity(Gravity.CENTER);
            tvDesc.setVisibility(View.GONE);
        } else {
            if(row.getTitle() != null) {
                tvTitle.setText(row.getTitle());
            }
            if(row.getType() != null) {
                tvDesc.setText(row.getType());
            }
        }
    }

    return v;
}

所以我的問題是，為什么這種樣式會隨機排列行而不是我告訴它的行？

Answer 1

if(mainList.get(position) instanceof Program) {
        Program row = (Program) mainList.get(position);
        if(row.getTitle() != null && row.getType() == null) {
            //this condition should style just the ones with null type, but style random rows instead
            tvTitle.setVisibility(View.VISIBLE);
            tvTitle.setText(row.getTitle());
            tvTitle.setGravity(Gravity.CENTER);
            tvDesc.setVisibility(View.GONE);
        } else {
            tvTitle.setVisibility(View.GONE);
            tvTitle.setGravity(Gravity.LEFT);
            tvDesc.setVisibility(View.VISIBLE);
            if(row.getTitle() != null) {
                tvTitle.setText(row.getTitle());
            }
            if(row.getType() != null) {
                tvDesc.setText(row.getType());
            }
        }
    }