Here you can find the source of toDouble(Object value)
public static final double toDouble(Object value)
//package com.java2s; public class Main { public static final double toDouble(Object value) { if (value instanceof Number) return ((Number) value).doubleValue(); else if (value == null) return 0; else/*from w w w. ja va 2 s . c o m*/ return Double.parseDouble(value.toString()); } public static final String toString(Object value) { if (value == null) return null; return value.toString(); } }