如何计算一个总数取决于用户在组合框中的seletcs？

Question

我希望用户从组合框中选择选项，并根据他们选择的输出字段计算其中的价格。 例如，如果他们选择英特尔酷睿i5，它将增加50美元的计算价格

他们的错误是我的输出框只添加最高/最后的值在一起。

我的三个组合框的名字处理器，内存，磁盘

我要计算在价格被命名为输出

我主要就需要如何在我的组合框中选择该选项可以帮助盒子在if语句中

private void calculateButtonActionPerformed(java.awt.event.ActionEvent evt) {             

    double price; //initilize variable 
    double windowsUpgrade; //Initilize variable 
    double processorPrice; 
    double memoryPrice; 
    double diskPrice; 

    if(Processor.getSelectedItem().equals("Intel Core i3")); 
    { 
     processorPrice = 0; 
    } 

    if(Processor.getSelectedItem().equals("Intel Core i5")); 
    { 
     processorPrice = 50; 
    } 

    if(Processor.getSelectedItem().equals("Intel Core i7")); 
    { 
     processorPrice = 150; 
    } 

    if(Memory.getSelectedItem().equals("4GB")); 
    { 
     memoryPrice = 0; 
    } 

    if(Memory.getSelectedItem().equals("8GB")); 
    { 
     memoryPrice = 50; 
    } 

    if(Memory.getSelectedItem().equals("16GB")); 
    { 
     memoryPrice = 100; 
    } 

    if(Memory.getSelectedItem().equals("32GB")); 
    { 
     memoryPrice = 150; 
    } 

    if(Disk.getSelectedItem().equals("1TB")); 
    { 
     diskPrice = 0; 
    } 


    if(Disk.getSelectedItem().equals("2TB")); 
    { 
     diskPrice = 50; 
    } 

    if(Disk.getSelectedItem().equals("512GB SSD")); 
    { 
     diskPrice = 150; 
    } 


    double calculation; 

    calculation = processorPrice + memoryPrice + diskPrice; 

    NumberFormat currency = NumberFormat.getCurrencyInstance(); 
String message = 
    currency.format(calculation); 

    Output.setText(message); 



}            

这是代码。

Answer 1

您可以使用对您的选择作出反应的监听器。

import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.ItemEvent; 
import java.awt.event.ItemListener; 

class ComboBoxTest 
{ 
    //A reference to the UI class where you initialize the buttons, 
    //combo box etc 
    private ComboBoxUI _ui; 

    private double _processorPrice; 
    private double _memoryPrice; 
    private double _diskPrice; 

    public ComboBoxTest() 
    { 
     _processorPrice = 0; 
     _memoryPrice = 0; 
     _diskPrice = 0; 
     _ui = new ComboBoxUI(); 
     registerListener(); 
    } 

    //Register three different comboBoxes and a button for 
    //the calculation to listener 
    private void registerListener() 
    { 
     _ui.getProcessorBox().addItemListener(new ItemListener() 
     { 
      @Override 
      public void itemStateChanged(ItemEvent e) 
      { 
       if (e.getItem().equals("Intel Core i3")) 
       { 
        _processorPrice = 0; 
       } 
       else if (e.getItem().equals("Intel Core i5")) 
       { 
        _processorPrice = 50; 
       } 
       else if (e.getItem().equals("Intel Core i7")) 
       { 
        _processorPrice = 150; 
       } 
      } 
     }); 

     _ui.getMemoryBox().addItemListener(new ItemListener() 
     { 
      @Override 
      public void itemStateChanged(ItemEvent e) 
      { 
       if (e.getItem().equals("4GB")) 
       { 
        _memoryPrice = 0; 
       } 
       else if (e.getItem().equals("8GB")) 
       { 
        _memoryPrice = 50; 
       } 
       else if (e.getItem().equals("16GB")) 
       { 
        _memoryPrice = 100; 
       } 
       else if (e.getItem().equals("32GB")) 
       { 
        _memoryPrice = 150; 
       } 
      } 
     }); 

     _ui.getDiscBox().addItemListener(new ItemListener() 
     { 
      @Override 
      public void itemStateChanged(ItemEvent e) 
      { 
       if (e.getItem().equals("1TB")) 
       { 
        _diskPrice = 0; 
       } 
       else if (e.getItem().equals("2TB")) 
       { 
        _diskPrice = 50; 
       } 
       else if (e.getItem().equals("512GB SSD")) 
       { 
        _diskPrice = 150; 
       } 
      } 
     }); 

     //getCalcButton() is a new Button that calcualtes the price 
     _ui.getCalcButton().addActionListener(new ActionListener() 
     { 
      @Override 
      public void actionPerformed(ActionEvent e) 
      { 
       System.out.println(_processorPrice + _memoryPrice + _diskPrice); 
      } 
     }); 
    } 
} 

用我的例子，你需要一个你的组件的UI类。像这样的东西:)

import java.awt.BorderLayout; 

import javax.swing.*; 

public class ComboBoxUI 
{ 
    JFrame _frame; 
    JPanel _componentPanel; 

    JButton _calcButton; 

    JComboBox _procBox; 
    JComboBox _memBox; 
    JComboBox _discBox; 

    ComboBoxUI() 
    { 
     initFrame(); 
     initComponenentPanel(); 
     showGui(); 
    } 

    //initialize a new JFrame with BorderLayout in this example 
    private void initFrame() 
    { 
     _frame = new JFrame("Title"); 
     _frame.setLayout(new BorderLayout()); 
    } 

    //initialize a new JPanel with your components like comboBox, buttons... 
    private void initComponenentPanel() 
    { 
     _componentPanel = new JPanel(); 

     String[] proc = { "Intel Core i3", "Intel Core i5", "Intel Core i7"}; 
     _procBox = new JComboBox(proc); 

     String[] memory = { "4GB", "8GB", "16GB", "32GB"}; 
     _memBox = new JComboBox(memory); 

     String[] disc = { "1TB", "2TB", "512GB SSD"}; 
     _discBox = new JComboBox(disc); 

     _calcButton = new JButton("Calculate"); 

     _componentPanel.add(_procBox); 
     _componentPanel.add(_memBox); 
     _componentPanel.add(_discBox); 
     _componentPanel.add(_calcButton); 

     _frame.add(_componentPanel, BorderLayout.NORTH); 
    } 

    //Set the size of your JFrame and make it visible 
    private void showGui() 
    { 
     _frame.setSize(500, 200); 
     _frame.setVisible(true); 
     _frame.setDefaultCloseOperation(_frame.EXIT_ON_CLOSE); 
    } 


    public JComboBox getProcessorBox() 
    { 
     return _procBox; 
    } 

    public JComboBox getMemoryBox() 
    { 
     return _memBox; 
    } 

    public JComboBox getDiscBox() 
    { 
     return _discBox; 
    } 

    public JButton getCalcButton() 
    { 
     return _calcButton; 
    } 
}