Question

我的代码在这里：

public void Edit()throws IOException{
        FileWriter writeFile=new FileWriter("voters.txt", true);
        BufferedWriter outFile=new BufferedWriter(writeFile);
        File readFile=new File("voters.txt");
        BufferedReader read=new BufferedReader(new FileReader(readFile));

        vNumForEdit=JOptionPane.showInputDialog("Enter voters number: ");
        String line=null;
        while((line=read.readLine())!=null){
            String [] info=line.split("/");
            if(info[0].matches(vNumForEdit)){
                String [] forEditMenu={"Name", "Age", "Gender", "Date of Birth", "Place of Birth", "Address", "Civil Status", "Citizenship", "Profession/Occupation", "Father's Name", "Mother's Name"};
                forEdit=(String)JOptionPane.showInputDialog(null, line+"\n\nPlease select what you want to edit", "National Election 2765", 1, null, forEditMenu, forEditMenu[0]);
                switch(forEdit){
                case "Name":
                    newName=JOptionPane.showInputDialog("Enter new name: ");
                    if(info[1].matches(oldName)){
                        outFile.append(info[1]=newName);
                        outFile.close();
                    }
                    read.close();

                    break;
                }
            }
        }
    }

文本文件如下所示

1/d/19/Male/e//s/Single/v/e/e/f
2/c/98/Male//d/c/Single/r/w/q/d

你可以看到我将info / line作为数组，因此它可以读取索引0中的值，即投票号。任务是用户将输入选民号码，然后如果找到，用户将再次输入他想要编辑的内容。我也使用数组来确定名称，年龄，性别等。数组是这样的：

info[0] = voters number
info[1]= name
info[2] = age
info[3] = date of birth
info[4]= place of birth
info[5] = status
info[6] = citizenship
info[7] = profession
info[8] = father's name
info[9] = mother's name

但我的代码总是以错误java.lang.NullPointerException结束。我的大多数变量都是全局声明的

编辑：这是错误/堆栈跟踪

Exception in thread "main" java.lang.NullPointerException
    at java.util.regex.Pattern.<init>(Unknown Source)
    at java.util.regex.Pattern.compile(Unknown Source)
    at java.util.regex.Pattern.matches(Unknown Source)
    at java.lang.String.matches(Unknown Source)
    at lozada.My_Voting_System_Official.Edit(My_Voting_System_Official.java:135)
    at lozada.My_Voting_System_Official.Menu(My_Voting_System_Official.java:43)
    at lozada.My_Voting_System_Official.main(My_Voting_System_Official.java:15)

Answer 1

我认为您没有声明oldName变量在此代码中

if(info[1].matches(oldName)){
                        outFile.append(info[1]=newName);
                        outFile.close();
                    }

替换文本文件java中的单词

1 个答案: