VB.net で 乱数生成

Dim rand As New System.Random()
Dim ret as Integer

'0 以上の乱数'
ret = rand.Next()

'0以上 1000未満の乱数'
ret = rand.Next(1000)

'1000以上 9999未満の乱数'
ret = rand.Next(1000, 9999)

Dim rand As New System.Random()
Dim ret2 as Double

'0.0以上 1.0未満の乱数'
ret2 = rand.NextDouble()