How to change the editText line colors programmatically?

Question

I use this class to make lines inside editText which works well. I want to change the line colors in another activities programmatically. How to do that?

public  class LinedEditText extends androidx.appcompat.widget.AppCompatEditText{
    public final Paint mPaint = new Paint();

    public LinedEditText(Context context) {
        super(context);
        initPaint();
    }

    public LinedEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
        initPaint();
    }

    public LinedEditText(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initPaint();
    }

    private void initPaint() {
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(Color.BLUE);
    }

    @Override protected void onDraw(Canvas canvas) {
        int left = getLeft();
        int right = getRight();
        int paddingTop = getPaddingTop();
        int paddingBottom = getPaddingBottom();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        int height = getHeight();
        int lineHeight = getLineHeight();
        int count = (height-paddingTop-paddingBottom) / lineHeight;

        for (int i = 0; i < count; i++) {
            int baseline = lineHeight * (i+1) + paddingTop;
            canvas.drawLine(left+paddingLeft, baseline, right-paddingRight, baseline, mPaint);
        }

        super.onDraw(canvas);
    }
}

Second question is, how to make new line when the user pressed enter or return key so as to the will have something like unlimited lines?

Answer 1

public  class LinedEditText extends EditText {

private Rect mRect;
protected Paint mPaint;

// we need this constructor for LayoutInflater
public LinedEditText(Context context, AttributeSet attrs) {
    super(context, attrs);

    mRect = new Rect();
    mPaint = new Paint();
    mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
    mPaint.setColor(Color.parseColor("#82B6C6"));
}

@Override
public void onDraw(Canvas canvas) {
    //int count = getLineCount();

    int height = getHeight();
    int line_height = getLineHeight();

    int count = height / line_height;

    if (getLineCount() > count)
        count = getLineCount();//for long text with scrolling


    Rect r = mRect;
    Paint paint = mPaint;
    int baseline = getLineBounds(0, r);//first line

    for (int i = 0; i < count; i++) {

        canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
        baseline += getLineHeight();//next line
    }

    super.onDraw(canvas);
}

}