錯誤：類型不匹配：不能從空轉變爲java.lang.String

Question

我不斷收到此錯誤：

Type mismatch: cannot convert from void to java.lang.String for my dialog box.

我試圖讓名在對話框中與計算露面，但我得到上面的錯誤。

public static void main(String[] args) 
    { 
    final double tax_Rate = .08; 
    final double bonus_Pay_Rate = .1; 
    String name = JOptionPane.showInputDialog("Please enter your name"); 
    String hr = JOptionPane.showInputDialog("Please enter your hourly rate"); 
    double hourlyRate = Double.parseDouble(hr); 
    String hw = JOptionPane.showInputDialog("Please enter your hours worked"); 
    double hoursWorked = Double.parseDouble(hw); 
    double tax = (hoursWorked * hourlyRate) * tax_Rate; 
    double pay = hoursWorked * hourlyRate - tax; 
    double weeksPay = (pay * bonus_Pay_Rate) + pay; 
    String aswner = JOptionPane.showMessageDialog(null, (name) + "'s" + "pay this week is: $" + (weeksPay)); 

Answer 1

您試圖將void分配給String。

String aswner = JOptionPane.showMessageDialog(null,...); 

showMessageDialog返回void，而不是一個String。

https://docs.oracle.com/javase/7/docs/api/javax/swing/JOptionPane.html