对Map中的值求和

Question

如何将给定地图中的所有值加在一起？

private final Map<String, Double> deviceVoltageMap = new HashMap<String, Double>();

synchronized public double getVoltage(String device) {
    double totalVolts = 0.0;
    for (String key : deviceVoltageMap.keySet()) {
         //?
        }
    return totalVolts;
}

Answer 1

使用Map#values()!迭代值!