Java初始化变量错误

Question

我收到一个错误，提示我尚未初始化 buffer.write(variable); 行中的firSTLine、secondLine 和thirdLine 变量，其中变量为firstLine、secondLine 和thirdLine。直到我在 variable == JOptionPane.showInputDialog("Enter name"); 周围添加 while(number == null || number.equals("")) 后，此错误才出现。我的代码中的 行。有什么方法可以在保留我添加的代码的同时处理此错误吗？

    import java.awt.Graphics;   
    import javax.swing.JOptionPane;
    import java.io.*;
    import java.io.FileWriter; 

    public class CreateData {

    public static void main(String[] args)
    {

        JOptionPane.showMessageDialog(null, 
          "this program writes payroll data",
          "Welcome", JOptionPane.PLAIN_MESSAGE);

        Write();
    }

    static void Write()
    {
      try {  
        String firstLine, secondLine, thirdLine, number = " ";
        File check = new File("payroll.txt");  
        FileWriter file;
        if(check.exists()) 
          file = new FileWriter("payroll.txt", true);
        else
          file = new FileWriter("payroll.txt"); 

        BufferedWriter buffer = new BufferedWriter(file);
        int size, count = 1;
        while(number == null || number.equals("")) 
        {
        number = JOptionPane.showInputDialog("how many records?");
        }

        size = Integer.parseInt(number);

         do { 
          while(number == null || number.equals("")) 
          {
          firstLine = JOptionPane.showInputDialog("Enter name");// prompts for input and displays "Enter Name"
          }
          while(number == null || number.equals("")) 
          {
          secondLine = JOptionPane.showInputDialog("Enter hours");
          }
          while(number == null || number.equals("")) 
          {     
          thirdLine = JOptionPane.showInputDialog("Enter wage");
          }
          buffer.write(firstLine);//write firstLine variable to payroll.txt file
          buffer.newLine();
          buffer.write(secondLine);
          buffer.newLine();
          buffer.write(thirdLine);
          buffer.newLine();
          count++;

        }while(count <= size);

        buffer.close();//closes the data writing stream to payroll.txt file

        JOptionPane.showMessageDialog(null, "data processed",
        "Result", JOptionPane.PLAIN_MESSAGE );//display message "data processed"

        System.exit(1);
        }

      catch (IOException e) { System.out.println(e); }  


    }
    }

Answer 1

这一行

String firstLine, secondLine, thirdLine, number = " ";

等于

String firstLine;
String secondLine;
String thirdLine;
String number = " ";

所以你需要初始化你的firstLine、secondLine、thirdLine:

String firstLine = "";
String secondLine = "";
String thirdLine = "";
String number = " ";