一:在java中,自定義類想要比較需要實(shí)現(xiàn)Comparable接口,并重寫compareTo方法
二:可以使用工具類Collections.sort(haoHanArrayList);對(duì)自定義集合進(jìn)行排序
三:除以2,可以使用乘以0.5f,這樣不容易丟失精度
四:要讓字母顯示在父控件的中間,可以如下:
//1 繪制 A-Z 26個(gè)字母 for (int i = 0; i < LETTERS.length; i++) { mPaint.setColor(i == lastTouchIndex ? Color.GREEN : Color.WHITE); //獲取到字母的邊界矩形 Rect rect = new Rect(); mPaint.getTextBounds(LETTERS[i], 0, LETTERS[i].length(), rect); //把字母畫在單元格的中間 float x = ceilWidth * 0.5f - rect.width() * 0.5f; float y = ceilHeight * 0.5f + rect.height() * 0.5f + i * ceilHeight; canvas.drawText(LETTERS[i], x, y, mPaint); }五:判斷觸摸到哪個(gè)字母,并且提高效率
//判斷觸摸到了哪個(gè)字母 float downY = event.getY(); currentTouchIndex = (int) (downY / ceilHeight); if (currentTouchIndex != lastTouchIndex) { if (currentTouchIndex >= 0 && currentTouchIndex < LETTERS.length) { lastTouchIndex = currentTouchIndex; Utils.showToast(getContext(), LETTERS[lastTouchIndex]); if (mOnLetterChangeListener != null) { mOnLetterChangeListener.onLetterChange(LETTERS[lastTouchIndex]); } } }六:理解監(jiān)聽回調(diào)的步驟,一般自定義view肯定會(huì)用到
public void setOnLetterChangeListener(OnLetterChangeListener mOnLetterChangeListener) { this.mOnLetterChangeListener = mOnLetterChangeListener; } PRivate OnLetterChangeListener mOnLetterChangeListener; interface OnLetterChangeListener { void onLetterChange(String letter); }七:一般可以在onSizeChanged()方法中去拿到控件的寬高,并做處理
@Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { //每一個(gè)字母單元格的高度 ceilHeight = h * 1.0f / LETTERS.length; //每一個(gè)字母單元格的寬度 ceilWidth = w; }八:在觸摸的時(shí)候讓listView跟隨滾動(dòng),可以先獲取到listview滾動(dòng)到的位置,然后listView.setSelection(position);
qiv.setOnLetterChangeListener(new QuickIndexerView.OnLetterChangeListener() { @Override public void onLetterChange(String letter) { //找到listview需要滾動(dòng)到的位置 for (int i = 0; i < haoHanArrayList.size(); i++) { if (letter.equals(haoHanArrayList.get(i).getFirstLetter())) { listView.setSelection(i); tv_header.setText(haoHanArrayList.get(i).getFirstLetter()); break; } } }});九:listview的懸浮標(biāo)題通常可以用表頭布局覆蓋在listview頂部,然后在OnScrollListener中去修改值
listView.setOnScrollListener(new AbsListView.OnScrollListener() { @Override public void onScrollStateChanged(AbsListView view, int scrollState) { } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { tv_header.setText(haoHanArrayList.get(firstVisibleItem).getFirstLetter()); }});十:在listview的Adapter的getview方法中,如果有需要比較上下兩個(gè)條目,可以把第一條分開來
if(position == 0) {}else{}這樣不容易數(shù)組越界
十一:移除handler之前的延時(shí)操作:mHandler.removeCallbacksAndMessages(null);
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