Android :: List Item Order Changes Unexpectedly While Scrolling

I am new to android, and ended up (have to) ask a question here, Let's make it simple, I simply want to make my own TextView-like (MyView extends View). This is my code:

public class MyView extends View { private Paint mPaint; private String mText;
private Bitmap mBitmap1; private Bitmap mBitmap2; public MyView(Context context) {
super(context); initView(); } public MyView(Context context, AttributeSet attrs) {
super(context, attrs); initView(); } private final void initView() {
mPaint = new Paint(); } public void setText(String text) { mText = text;
} @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int measuredWidth = measureWidth(widthMeasureSpec);
if (mBitmap1 == null) initBitmap1(measuredWidth);
int measuredHeight = measureHeight(heightMeasureSpec);
setMeasuredDimension(measuredWidth, measuredHeight);
} private void initBitmap1(int measuredWidth) {
mBitmap1 = Bitmap.createBitmap(measuredWidth, Fonts.getHeight(), Bitmap.Config.ARGB_4444);
Canvas canvas = new Canvas(mBitmap1 ); canvas.drawText(mText, 0, 0, mPaint);
} private void initBitmap2() { mBitmap2 = Bitmap.createBitmap(30,
Fonts.getHeight(), Bitmap.Config.ARGB_4444); Canvas canvas = new Canvas(mBitmap2;
canvas.drawText(mText, 0, 0, mPaint);}
private int measureWidth(int widthMeasureSpec) { int measuredWidth = 0;
int specWidthMode = MeasureSpec.getMode(widthMeasureSpec);
int specWidthSize = MeasureSpec.getSize(widthMeasureSpec);
if (specWidthMode == MeasureSpec.EXACTLY) { measuredWidth = specWidthSize;
} else { measuredWidth = getWidth(); if (specWidthMode == MeasureSpec.AT_MOST) {
measuredWidth = Math.min(measuredWidth, specWidthSize);
} } return measuredWidth; }
private int measureHeight(int heightMeasureSpec) {
int measuredHeight = 0; int specHeightMode = MeasureSpec.getMode(heightMeasureSpec);
int specHeightSize = MeasureSpec.getSize(heightMeasureSpec);
if (specHeightMode == MeasureSpec.EXACTLY) {
measuredHeight = specHeightSize; } else { measuredHeight = 80;
if (specHeightMode == MeasureSpec.AT_MOST) { measuredHeight = Math.min(measuredHeight, specHeightSize);
} } return measuredHeight; }
@Override protected void onDraw(Canvas canvas) {
super.onDraw(canvas); canvas.drawBitmap(mBitmap1, getLeft(), 0, mPaint);
initBitmap2(); canvas.drawBitmap(mBitmap2, getLeft(), 30, mPaint); } }