我先画了一条线，然后画了一个点，然后我要检查该点是否在线上。我已经在数组中取得了一条线坐标（因为有多条线）。我想在最后一行检查当前点吗？

if (positionX1 == positionX2 && positionY1 == positionY2) {
    float m = line.getSlope(
        drawLines[currentLines - 1][2], drawLines[currentLines - 1][3],
        drawLines[currentLines - 1][0], drawLines[currentLines - 1][1]);
    m = Float.parseFloat(df.format(m));
    float c = line.getIntercept(
        drawLines[currentLines - 1][2], drawLines[currentLines - 1][3],
        drawLines[currentLines - 1][0], drawLines[currentLines - 1][1]);
    c = Math.round(c);
    m1 = line.getSlope(positionX2, positionY2,
        drawLines[currentLines - 1][0], drawLines[currentLines - 1][1]);
    m1 = Float.parseFloat(df.format(m1));
    System.out.println(m + "   " + m1);
    c1 = line.getIntercept(positionX2, positionY2,
        drawLines[currentLines - 1][0], drawLines[currentLines - 1][1]);
    c1 = Math.round(c1);

    if (m == m1 && ((c == c1) || (c == c1 - 1) || (c == c1 + 1))) {
        System.out.println("Point is on Line");
    }
}

问题是当一点在直线的起点附近或直线大约在m1和c1的垂直值相差很大时。因此，检测点是否在线上存在一个问题。我如何检查这种情况？