在Java中将BigDecimal添加到BigDecimal
我没法让它工作。我写了一些笔记,希望能解释我正在尝试做什么。控制台在totalCost = totalCost.add(new BigDecimal(result));
行输出一个错误
private void btn_motherboardActionPerformed(java.awt.event.ActionEvent evt) {
String cost = cb_motherboard.getSelectedItem().toString();
//gets item from combobox. Makes a string
Components.addElement(cost);// adds string to model
lb_computer_components.setModel(Components);//sets model to jlist
String result = cost.substring(cost.lastIndexOf('£') + 1);
//creates a substring containing information after £ (for example 45.99)
totalCost = totalCost.add(new BigDecimal(result));
//totalcost is a public bigdecimal, i want to add 45.99 to it in this example
String BD = totalCost.toString();
//change the new totalcost to a string
String stringTotal = n.format(BD);
//format that string to a currency
txt_total_computer.setText(stringTotal);
//output that string to a textfield
}
# 1 楼答案
之所以会出现这种情况,是因为
totalCost
为空,然后您试图使用它引用的对象您应该做的是将这一行添加到类的构造函数中