安卓EditText中控制光标上移或下移一行

//UpDown 0:光标上移 1：光标下移
public boolean moveUpDown(EditText myTextbox,int UpDown) {
		int start = myTextbox.getSelectionStart();
		int end = myTextbox.getSelectionEnd();
		Layout layout = myTextbox.getLayout();
		if (start != end) {
			int min = Math.min(start, end);
			int max = Math.max(start, end);
            if(UpDown==0)
				myTextbox.setSelection(min);
			else
				myTextbox.setSelection(max);
 
			if (min == 0 && max == myTextbox.length()) {
				return false;
			}
 
			return true;
		} else {
			int line = layout.getLineForOffset(end);
            if(UpDown==0)
			{
				if (line > 0) {
					  int move;
					 if (layout.getParagraphDirection(line) ==
					layout.getParagraphDirection(line - 1)) {
					float h = layout.getPrimaryHorizontal(end);
					 move = layout.getOffsetForHorizontal(line - 1, h);
					} else {
					 move = layout.getLineStart(line - 1);
					}
					myTextbox.setSelection(move);
                    return true;
                   }
			}
			else
			{
				if (line < layout.getLineCount() - 1) {
					int move;
 
					if (layout.getParagraphDirection(line) ==
							layout.getParagraphDirection(line + 1)) {
						float h = layout.getPrimaryHorizontal(end);
						move = layout.getOffsetForHorizontal(line + 1, h);
					} else {
						move = layout.getLineStart(line + 1);
					}
 
					myTextbox.setSelection(move);
					return true;
				}
			}
		}
 
		return false;
	}