如何摆脱动作事件中的空指针异常？

我正在尝试让按钮单击以将用户输入到文本框中的整数添加到另一个文本框中。即时通讯使用FXML和我已经设置的行动calculateTotal（）。当我点击按钮时，它正在运行我得到一个空指针excpetion虽然就行如何摆脱动作事件中的空指针异常？

int sal1 = Integer.parseInt(sale1.getText());

这是其余的代码。该错误所在的行在calculateTotal（）的底部。

package taxerfxml; 

import java.net.URL; 
import java.util.ResourceBundle; 
import javafx.collections.FXCollections; 
import javafx.collections.ObservableList; 
import javafx.event.ActionEvent; 
import javafx.event.EventHandler; 
import javafx.fxml.FXML; 
import javafx.fxml.Initializable; 
import javafx.scene.control.Button; 
import javafx.scene.control.ComboBox; 
import javafx.scene.control.Label; 
import javafx.scene.control.TextField; 
import javax.swing.JComboBox; 
import static sun.misc.Signal.handle; 


/** 
* 
* @author 
*/ 
public class FXMLDocumentController implements Initializable { 
    ObservableList<String> comboBoxList = FXCollections.observableArrayList("Ccosta", "Alam", "Sclara", "Smateo", "Sf", "Marin", "Sonoma", "Napa", "Solono"); 

//fxml combo boxes 
    @FXML 
    private ComboBox comboBox1; 
    @FXML 
    private ComboBox comboBox2; 
    @FXML 
    private ComboBox comboBox3; 
    @FXML 
    private ComboBox comboBox4; 
    @FXML 
    private ComboBox comboBox5; 
    @FXML 
    private ComboBox comboBox6; 
    @FXML 
    private ComboBox comboBox7; 
    @FXML 
    private ComboBox comboBox8; 
    @FXML 
    private ComboBox comboBox9; 
    @FXML 
    private ComboBox comboBox10; 
    @FXML 
    private ComboBox comboBox11; 
    @FXML 
    private ComboBox comboBox12; 

//fxml labels 
    @FXML 
    private Label sale;  
    @FXML 
    private Label tax; 
    @FXML 
    private Label county; 
    @FXML 
    private Label freight; 
    @FXML 
    private Label labor; 
    @FXML 
    private Label cost; 
    @FXML 
    private Label profit; 
    @FXML 
    private Label customer; 

    // fxml customer textfields 
    @FXML 
    private TextField customer1; 
    @FXML 
    private TextField customer2; 
    @FXML 
    private TextField customer3; 
    @FXML 
    private TextField customer4; 
    @FXML 
    private TextField customer5; 
    @FXML 
    private TextField customer6; 
    @FXML 
    private TextField customer7; 
    @FXML 
    private TextField customer8; 
    @FXML 
    private TextField customer9; 
    @FXML 
    private TextField customer10; 
    @FXML 
    private TextField customer11; 
    @FXML 
    private TextField customer12; 

    //fxml sale textfields 

    @FXML 
    private TextField sale1; 
    @FXML 
    private TextField sale2; 
    @FXML 
    private TextField sale3; 
    @FXML 
    private TextField sale4; 
    @FXML 
    private TextField sale5; 
    @FXML 
    private TextField sale6; 
    @FXML 
    private TextField sale7; 
    @FXML 
    private TextField sale8; 
    @FXML 
    private TextField sale9; 
    @FXML 
    private TextField sale10; 
    @FXML 
    private TextField sale11; 
    @FXML 
    private TextField sale12; 

    //fxml tax textfields 

    @FXML 
    private TextField tax1; 
    @FXML 
    private TextField tax2; 
    @FXML 
    private TextField tax3; 
    @FXML 
    private TextField tax4; 
    @FXML 
    private TextField tax5; 
    @FXML 
    private TextField tax6; 
    @FXML 
    private TextField tax7; 
    @FXML 
    private TextField tax8; 
    @FXML 
    private TextField tax9; 
    @FXML 
    private TextField tax10; 
    @FXML 
    private TextField tax11; 
    @FXML 
    private TextField tax12; 

    //fxml freight textfields 
    @FXML 
    private TextField freight1; 
    @FXML 
    private TextField freight2; 
    @FXML 
    private TextField freight3; 
    @FXML 
    private TextField freight4; 
    @FXML 
    private TextField freight5; 
    @FXML 
    private TextField freight6; 
    @FXML 
    private TextField freight7; 
    @FXML 
    private TextField freight8; 
    @FXML 
    private TextField freight9; 
    @FXML 
    private TextField freight10; 
    @FXML 
    private TextField freight11; 
    @FXML 
    private TextField freight12; 

    //fxml labor textfields 
    @FXML 
    private TextField labor1; 
    @FXML 
    private TextField labor2; 
    @FXML 
    private TextField labor3; 
    @FXML 
    private TextField labor4; 
    @FXML 
    private TextField labor5; 
    @FXML 
    private TextField labor6; 
    @FXML 
    private TextField labor7; 
    @FXML 
    private TextField labor8; 
    @FXML 
    private TextField labor9; 
    @FXML 
    private TextField labor10; 
    @FXML 
    private TextField labor11; 
    @FXML 
    private TextField labor12; 

    //fxml cost textfields 
    @FXML 
    private TextField cost1; 
    @FXML 
    private TextField cost2; 
    @FXML 
    private TextField cost3; 
    @FXML 
    private TextField cost4; 
    @FXML 
    private TextField cost5; 
    @FXML 
    private TextField cost6; 
    @FXML 
    private TextField cost7; 
    @FXML 
    private TextField cost8; 
    @FXML 
    private TextField cost9; 
    @FXML 
    private TextField cost10; 
    @FXML 
    private TextField cost11; 
    @FXML 
    private TextField cost12; 

    //fxml profit textfields 
    @FXML 
    private TextField profit1; 
    @FXML 
    private TextField profit2; 
    @FXML 
    private TextField profit3; 
    @FXML 
    private TextField profit4; 
    @FXML 
    private TextField profit5; 
    @FXML 
    private TextField profit6; 
    @FXML 
    private TextField profit7; 
    @FXML 
    private TextField profit8; 
    @FXML 
    private TextField profit9; 
    @FXML 
    private TextField profit10; 
    @FXML 
    private TextField profit11; 
    @FXML 
    private TextField profit12; 

    //fxml button calculate 
    @FXML 
    private Button calculate; 




    @Override 
    public void initialize(URL url, ResourceBundle rb) { 



     //initialize combobox variables 
     comboBox1.setValue("County"); 
     comboBox1.setItems(comboBoxList); 

     comboBox2.setValue("County"); 
     comboBox2.setItems(comboBoxList); 

     comboBox3.setValue("County"); 
     comboBox3.setItems(comboBoxList); 

     comboBox4.setValue("County"); 
     comboBox4.setItems(comboBoxList); 

     comboBox5.setValue("County"); 
     comboBox5.setItems(comboBoxList); 

     comboBox6.setValue("County"); 
     comboBox6.setItems(comboBoxList); 

     comboBox7.setValue("County"); 
     comboBox7.setItems(comboBoxList); 

     comboBox8.setValue("County"); 
     comboBox8.setItems(comboBoxList); 

     comboBox9.setValue("County"); 
     comboBox9.setItems(comboBoxList); 

     comboBox10.setValue("County"); 
     comboBox10.setItems(comboBoxList); 

     comboBox11.setValue("County"); 
     comboBox11.setItems(comboBoxList); 

     comboBox12.setValue("County"); 
     comboBox12.setItems(comboBoxList); 
    } 

     @FXML 
     public void calculateTotal(ActionEvent event){ 

     //add values put into textfields 
     // calculateTotal.setOnAction(new EventHandler<ActionEvent>() { 
     // if(event.getSource()==calculateTotal){ 

     //row1 
     int sal1 = Integer.parseInt(sale1.getText()); 
     int taxx1 = Integer.parseInt(tax1.getText()); 
     int frei1 = Integer.parseInt(freight1.getText()); 
     int lab1 = Integer.parseInt(labor1.getText()); 
     int cos1 = Integer.parseInt(cost1.getText());   
     int result1 = sal1 + taxx1 + frei1 + lab1 + cos1; 
     profit1.setText(profit1.getText()+result1); 


     //row2 
     int sal2 = Integer.parseInt(sale2.getText()); 
     int taxx2 = Integer.parseInt(tax2.getText()); 
     int frei2 = Integer.parseInt(freight2.getText()); 
     int lab2 = Integer.parseInt(labor2.getText()); 
     int cos2 = Integer.parseInt(cost2.getText());   
     int result2 = sal2 + taxx2 + frei2 + lab2 + cos2; 
     profit2.setText(profit2.getText()+result2);  

     //row3 
     int sal3 = Integer.parseInt(sale3.getText()); 
     int taxx3 = Integer.parseInt(tax3.getText()); 
     int frei3 = Integer.parseInt(freight3.getText()); 
     int lab3 = Integer.parseInt(labor3.getText()); 
     int cos3 = Integer.parseInt(cost3.getText());   
     int result3 = sal3 + taxx3 + frei3 + lab3 + cos3; 
     profit3.setText(profit3.getText()+result3); 

     //row4 
     int sal4 = Integer.parseInt(sale4.getText()); 
     int taxx4 = Integer.parseInt(tax4.getText()); 
     int frei4 = Integer.parseInt(freight4.getText()); 
     int lab4 = Integer.parseInt(labor4.getText()); 
     int cos4 = Integer.parseInt(cost4.getText());   
     int result4 = sal4 + taxx4 + frei4 + lab4 + cos4; 
     profit4.setText(profit4.getText()+result4); 

     //row5 
     int sal5 = Integer.parseInt(sale5.getText()); 
     int taxx5 = Integer.parseInt(tax5.getText()); 
     int frei5 = Integer.parseInt(freight5.getText()); 
     int lab5 = Integer.parseInt(labor5.getText()); 
     int cos5 = Integer.parseInt(cost5.getText());   
     int result5 = sal5 + taxx5 + frei5 + lab5 + cos5; 
     profit5.setText(profit5.getText()+result5); 

     //row6 
     int sal6 = Integer.parseInt(sale6.getText()); 
     int taxx6 = Integer.parseInt(tax6.getText()); 
     int frei6 = Integer.parseInt(freight6.getText()); 
     int lab6 = Integer.parseInt(labor6.getText()); 
     int cos6 = Integer.parseInt(cost6.getText());   
     int result6 = sal6 + taxx6 + frei6 + lab6 + cos6; 
     profit6.setText(profit6.getText()+result6); 

     //row7 
     int sal7 = Integer.parseInt(sale7.getText()); 
     int taxx7 = Integer.parseInt(tax7.getText()); 
     int frei7 = Integer.parseInt(freight7.getText()); 
     int lab7 = Integer.parseInt(labor7.getText()); 
     int cos7 = Integer.parseInt(cost7.getText());   
     int result7 = sal7 + taxx7 + frei7 + lab7 + cos7; 
     profit7.setText(profit7.getText()+result7); 

     //row8 
     int sal8 = Integer.parseInt(sale8.getText()); 
     int taxx8 = Integer.parseInt(tax8.getText()); 
     int frei8 = Integer.parseInt(freight8.getText()); 
     int lab8 = Integer.parseInt(labor8.getText()); 
     int cos8 = Integer.parseInt(cost8.getText());   
     int result8 = sal8 + taxx8 + frei8 + lab8 + cos8; 
     profit8.setText(profit8.getText()+result8); 

     //row9 
     int sal9 = Integer.parseInt(sale9.getText()); 
     int taxx9 = Integer.parseInt(tax9.getText()); 
     int frei9 = Integer.parseInt(freight9.getText()); 
     int lab9 = Integer.parseInt(labor9.getText()); 
     int cos9 = Integer.parseInt(cost9.getText());   
     int result9 = sal9 + taxx9 + frei9 + lab9 + cos9; 
     profit9.setText(profit9.getText()+result9); 

     //row10 
     int sal10 = Integer.parseInt(sale10.getText()); 
     int taxx10 = Integer.parseInt(tax10.getText()); 
     int frei10 = Integer.parseInt(freight10.getText()); 
     int lab10 = Integer.parseInt(labor10.getText()); 
     int cos10 = Integer.parseInt(cost10.getText());   
     int result10 = sal10 + taxx10 + frei10 + lab10 + cos10; 
     profit10.setText(profit10.getText()+result10); 

     //row11 
     int sal11 = Integer.parseInt(sale11.getText()); 
     int taxx11 = Integer.parseInt(tax11.getText()); 
     int frei11 = Integer.parseInt(freight11.getText()); 
     int lab11 = Integer.parseInt(labor11.getText()); 
     int cos11 = Integer.parseInt(cost11.getText());   
     int result11 = sal11 + taxx11 + frei11 + lab11 + cos11; 
     profit11.setText(profit11.getText()+result11); 

     //row12 
     int sal12 = Integer.parseInt(sale12.getText()); 
     int taxx12 = Integer.parseInt(tax12.getText()); 
     int frei12 = Integer.parseInt(freight12.getText()); 
     int lab12 = Integer.parseInt(labor12.getText()); 
     int cos12 = Integer.parseInt(cost12.getText());   
     int result12 = sal12 + taxx12 + frei12 + lab12 + cos12; 
     profit12.setText(profit12.getText()+result12); 




     } 


}

这是我的fxml文件。按钮是组合框

<?xml version="1.0" encoding="UTF-8"?> 

<?import javafx.scene.shape.*?> 
<?import java.lang.*?> 
<?import java.util.*?> 
<?import javafx.scene.*?> 
<?import javafx.scene.control.*?> 
<?import javafx.scene.layout.*?> 

<AnchorPane id="AnchorPane" prefHeight="615.0" prefWidth="1070.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="taxerfxml.FXMLDocumentController"> 
    <children> 
     <Accordion layoutX="14.0" layoutY="14.0" /> 
     <Label layoutX="238.0" layoutY="6.0" text="Sale" /> 
     <Label layoutX="358.0" layoutY="6.0" text="Tax" /> 
     <Label layoutX="491.0" layoutY="6.0" text="County" /> 
     <Label layoutX="622.0" layoutY="6.0" text="Freight" /> 
     <Label layoutX="741.0" layoutY="6.0" text="Labor" /> 
     <Label layoutX="857.0" layoutY="6.0" text="Cost" /> 
     <Label layoutX="994.0" layoutY="6.0" text="Profit" /> 
     <Label layoutX="14.0" layoutY="6.0" text="Customer" /> 
     <TextField layoutY="81.0" text="Customer 1" /> 
     <TextField layoutY="125.0" text="Customer 2" /> 
     <TextField layoutY="168.0" text="Customer 3" /> 
     <TextField layoutY="212.0" text="Customer 4" /> 
     <TextField layoutY="256.0" text="Customer 5" /> 
     <TextField layoutY="303.0" text="Customer 6" /> 
     <TextField layoutY="346.0" text="Customer 7" /> 
     <TextField layoutY="394.0" text="Customer 8" /> 
     <TextField layoutY="439.0" text="Customer 9" /> 
     <TextField layoutY="485.0" text="Customer 10" /> 
     <TextField layoutY="537.0" text="Customer 11" /> 
     <TextField layoutY="582.0" text="Customer 12" /> 
     <TextField layoutX="205.0" layoutY="83.0" prefHeight="25.0" prefWidth="88.0" text="Sale1" /> 
     <TextField layoutX="205.0" layoutY="127.0" prefHeight="25.0" prefWidth="88.0" text="Sale2" /> 
     <TextField layoutX="205.0" layoutY="170.0" prefHeight="25.0" prefWidth="88.0" text="Sale3" /> 
     <TextField layoutX="205.0" layoutY="214.0" prefHeight="25.0" prefWidth="88.0" text="Sale4" /> 
     <TextField layoutX="205.0" layoutY="258.0" prefHeight="25.0" prefWidth="88.0" text="Sale5" /> 
     <TextField layoutX="205.0" layoutY="305.0" prefHeight="25.0" prefWidth="88.0" text="Sale6" /> 
     <TextField layoutX="205.0" layoutY="348.0" prefHeight="25.0" prefWidth="88.0" text="Sale7" /> 
     <TextField layoutX="205.0" layoutY="396.0" prefHeight="25.0" prefWidth="88.0" text="Sale8" /> 
     <TextField layoutX="205.0" layoutY="441.0" prefHeight="25.0" prefWidth="88.0" text="Sale9" /> 
     <TextField layoutX="205.0" layoutY="487.0" prefHeight="25.0" prefWidth="88.0" text="Sale10" /> 
     <TextField layoutX="205.0" layoutY="539.0" prefHeight="25.0" prefWidth="88.0" text="Sale11" /> 
     <TextField layoutX="205.0" layoutY="584.0" prefHeight="25.0" prefWidth="88.0" text="Sale12" /> 
     <TextField layoutX="319.0" layoutY="83.0" prefHeight="25.0" prefWidth="97.0" text="Tax1" /> 
     <TextField layoutX="319.0" layoutY="127.0" prefHeight="25.0" prefWidth="97.0" text="Tax2" /> 
     <TextField layoutX="319.0" layoutY="168.0" prefHeight="25.0" prefWidth="97.0" text="Tax3" /> 
     <TextField layoutX="319.0" layoutY="214.0" prefHeight="25.0" prefWidth="97.0" text="Tax4" /> 
     <TextField layoutX="319.0" layoutY="258.0" prefHeight="25.0" prefWidth="97.0" text="Tax5" /> 
     <TextField layoutX="319.0" layoutY="305.0" prefHeight="25.0" prefWidth="97.0" text="Tax6" /> 
     <TextField layoutX="319.0" layoutY="348.0" prefHeight="25.0" prefWidth="97.0" text="Tax7" /> 
     <TextField layoutX="319.0" layoutY="394.0" prefHeight="25.0" prefWidth="97.0" text="Tax8" /> 
     <TextField layoutX="319.0" layoutY="441.0" prefHeight="25.0" prefWidth="97.0" text="Tax9" /> 
     <TextField layoutX="319.0" layoutY="487.0" prefHeight="25.0" prefWidth="97.0" text="Tax10" /> 
     <TextField layoutX="319.0" layoutY="539.0" prefHeight="25.0" prefWidth="97.0" text="Tax11" /> 
     <TextField layoutX="319.0" layoutY="584.0" prefHeight="25.0" prefWidth="97.0" text="Tax12" /> 
     <ComboBox id="comboBox1" fx:id="comboBox1" layoutX="466.0" layoutY="77.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox2" fx:id="comboBox2" layoutX="466.0" layoutY="120.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox3" fx:id="comboBox3" layoutX="466.0" layoutY="166.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox4" fx:id="comboBox4" layoutX="466.0" layoutY="210.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox5" fx:id="comboBox5" layoutX="466.0" layoutY="254.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox6" fx:id="comboBox6" layoutX="466.0" layoutY="301.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox7" fx:id="comboBox7" layoutX="466.0" layoutY="344.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox8" fx:id="comboBox8" layoutX="466.0" layoutY="392.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox9" fx:id="comboBox9" layoutX="466.0" layoutY="437.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox10" fx:id="comboBox10" layoutX="466.0" layoutY="483.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox11" fx:id="comboBox11" layoutX="466.0" layoutY="533.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <ComboBox id="comboBox12" fx:id="comboBox12" layoutX="466.0" layoutY="580.0" prefHeight="34.0" prefWidth="88.0" promptText="Choose" /> 
     <Button fx:id="calculate" layoutX="976.0" layoutY="23.0" mnemonicParsing="false" onAction="#calculateTotal" text="Calculate" /> 
     <TextField layoutX="597.0" layoutY="81.0" prefHeight="17.0" prefWidth="88.0" text="Freight1" /> 
     <TextField layoutX="597.0" layoutY="125.0" prefHeight="17.0" prefWidth="88.0" text="Freight2" /> 
     <TextField layoutX="597.0" layoutY="171.0" prefHeight="17.0" prefWidth="88.0" text="Freight3" /> 
     <TextField layoutX="597.0" layoutY="212.0" prefHeight="17.0" prefWidth="88.0" text="Freight4" /> 
     <TextField layoutX="597.0" layoutY="256.0" prefHeight="17.0" prefWidth="88.0" text="Freight5" /> 
     <TextField layoutX="597.0" layoutY="303.0" prefHeight="17.0" prefWidth="88.0" text="Freight6" /> 
     <TextField layoutX="597.0" layoutY="346.0" prefHeight="17.0" prefWidth="88.0" text="Freight7" /> 
     <TextField layoutX="597.0" layoutY="396.0" prefHeight="17.0" prefWidth="88.0" text="Freight8" /> 
     <TextField layoutX="597.0" layoutY="439.0" prefHeight="17.0" prefWidth="88.0" text="Freight9" /> 
     <TextField layoutX="597.0" layoutY="485.0" prefHeight="17.0" prefWidth="88.0" text="Freight10" /> 
     <TextField layoutX="597.0" layoutY="537.0" prefHeight="17.0" prefWidth="88.0" text="Freight11" /> 
     <TextField layoutX="597.0" layoutY="582.0" prefHeight="17.0" prefWidth="88.0" text="Freight12" /> 
     <TextField layoutX="712.0" layoutY="81.0" prefHeight="25.0" prefWidth="88.0" text="Labor1" /> 
     <TextField layoutX="712.0" layoutY="125.0" prefHeight="25.0" prefWidth="88.0" text="Labor2" /> 
     <TextField layoutX="712.0" layoutY="171.0" prefHeight="25.0" prefWidth="88.0" text="Labor3" /> 
     <TextField layoutX="713.0" layoutY="212.0" prefHeight="25.0" prefWidth="88.0" text="Labor4" /> 
     <TextField layoutX="713.0" layoutY="256.0" prefHeight="25.0" prefWidth="88.0" text="Labor5" /> 
     <TextField layoutX="713.0" layoutY="303.0" prefHeight="25.0" prefWidth="88.0" text="Labor6" /> 
     <TextField layoutX="713.0" layoutY="346.0" prefHeight="25.0" prefWidth="88.0" text="Labor7" /> 
     <TextField layoutX="713.0" layoutY="397.0" prefHeight="25.0" prefWidth="88.0" text="Labor8" /> 
     <TextField layoutX="713.0" layoutY="439.0" prefHeight="25.0" prefWidth="88.0" text="Labor9" /> 
     <TextField layoutX="713.0" layoutY="485.0" prefHeight="25.0" prefWidth="88.0" text="Labor10" /> 
     <TextField layoutX="713.0" layoutY="537.0" prefHeight="25.0" prefWidth="88.0" text="Labor11" /> 
     <TextField layoutX="713.0" layoutY="582.0" prefHeight="25.0" prefWidth="88.0" text="Labor12" /> 
     <TextField layoutX="825.0" layoutY="82.0" prefHeight="25.0" prefWidth="88.0" text="Cost1" /> 
     <TextField layoutX="825.0" layoutY="125.0" prefHeight="25.0" prefWidth="88.0" text="Cost2" /> 
     <TextField layoutX="825.0" layoutY="170.0" prefHeight="25.0" prefWidth="88.0" text="Cost3" /> 
     <TextField layoutX="825.0" layoutY="212.0" prefHeight="25.0" prefWidth="88.0" text="Cost4" /> 
     <TextField layoutX="825.0" layoutY="256.0" prefHeight="25.0" prefWidth="88.0" text="Cost5" /> 
     <TextField layoutX="825.0" layoutY="303.0" prefHeight="25.0" prefWidth="88.0" text="Cost6" /> 
     <TextField layoutX="825.0" layoutY="346.0" prefHeight="25.0" prefWidth="88.0" text="Cost7" /> 
     <TextField layoutX="825.0" layoutY="396.0" prefHeight="25.0" prefWidth="88.0" text="Cost8" /> 
     <TextField layoutX="825.0" layoutY="439.0" prefHeight="25.0" prefWidth="88.0" text="Cost9" /> 
     <TextField layoutX="825.0" layoutY="485.0" prefHeight="25.0" prefWidth="88.0" text="Cost10" /> 
     <TextField layoutX="825.0" layoutY="537.0" prefHeight="25.0" prefWidth="88.0" text="Cost11" /> 
     <TextField layoutX="825.0" layoutY="582.0" prefHeight="25.0" prefWidth="88.0" text="Cost12" /> 
     <TextField layoutX="952.0" layoutY="81.0" prefHeight="25.0" prefWidth="114.0" text="Profit1" /> 
     <TextField layoutX="952.0" layoutY="125.0" prefHeight="25.0" prefWidth="114.0" text="Profit2" /> 
     <TextField layoutX="952.0" layoutY="168.0" prefHeight="25.0" prefWidth="114.0" text="Profit3" /> 
     <TextField layoutX="952.0" layoutY="212.0" prefHeight="25.0" prefWidth="114.0" text="Profit4" /> 
     <TextField layoutX="952.0" layoutY="256.0" prefHeight="25.0" prefWidth="114.0" text="Profit5" /> 
     <TextField layoutX="952.0" layoutY="303.0" prefHeight="25.0" prefWidth="114.0" text="Profit6" /> 
     <TextField layoutX="952.0" layoutY="346.0" prefHeight="25.0" prefWidth="114.0" text="Profit7" /> 
     <TextField layoutX="952.0" layoutY="394.0" prefHeight="25.0" prefWidth="114.0" text="Profit8" /> 
     <TextField layoutX="952.0" layoutY="439.0" prefHeight="25.0" prefWidth="114.0" text="Profit9" /> 
     <TextField layoutX="952.0" layoutY="485.0" prefHeight="25.0" prefWidth="114.0" text="Profit10" /> 
     <TextField layoutX="952.0" layoutY="537.0" prefHeight="25.0" prefWidth="114.0" text="Profit11" /> 
     <TextField layoutX="952.0" layoutY="582.0" prefHeight="25.0" prefWidth="114.0" text="Profit12" /> 

    </children> 
</AnchorPane>

来源

2017-05-04 bills

这是因为sale1为空，你确定你有一个标签，所以在XML文档中，所以？ –

@ΦXocę웃Пepeúpaツ我添加了fxml文件。你是什么意思sale1是空的？对不起，这个新的 – bills

为了理解你的代码不工作的原因，考虑一下这样一个事实，即文本字段是在FXML文件中设置的，但是控制器没有办法知道哪个*巨大数量的）文本字段是'sale1'。要理解什么是空指针异常，请阅读http://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it。要了解如何解决这个特定的NPE，请阅读FXML /控制器上的任何介绍，例如http://stackoverflow.com/documentation/javafx/1580/fxml-and-controllers/5125/example-fxml#t=201705041156368117264 –

-1

我会假设，因为你已经与getText()函数获得的文本不能转换为整数，您收到此错误后。

您可以在其周围放置try声明。

例如

try { //it will attempt to convert the text 
... your code 
} catch (Exception e) { // if it fails the following code will happen 
... error response code 
}

编辑：

看来你的问题实际上未初始化的TextField。这里是一个职位，可以帮助How can a textfield from fxml file be updated by setText in java file?

这里是另一个How can I fix a NullPointerException when interacting with FXML elements in the start method?

来源

2017-05-04 06:21:49 JFreeman

它总是*错误显式初始化注释'@ FXML'的字段。此代码将摆脱NPE，但它不会产生所需的效果，因为它不会调用FXML文件中定义的文本字段上的方法。 –

是的，我编辑了我的文章，因为我误解他在使用'FXML'谢谢！ – JFreeman

我猜想FXML代码的120行和*超过100个'@ FXML' *注解很容易错过....它也是一个错误，以便捕获'NullPointerException's，因为那些代码实际上代表了不可恢复的错误当然在这种情况下，编程错误。您链接的帖子似乎完全不相关。 –

你得到空指针异常，因为你没有初始化sale1你只有decclared它。为更好地理解空指针异常请按照下面的链接： https://stackoverflow.com/a/218510/3420973

来源

2017-05-04 06:25:59 user3420973

我是否需要初始化为零，然后进行整数解析？ – bills

是在使用之前进行初始化。 – user3420973

如何摆脱动作事件中的空指针异常？

回答

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