为什么会抛出NUllPointerException？
本帖最后由 wjpxz 于 2013-01-24 10:44:05 编辑 异常发生在62行，这是异常代码：
Exception in thread "main" java.lang.NullPointerException
at java.io.Writer.write(Unknown Source)
at test.util.ComposeMessage.composeMessage(ComposeMessage.java:62)
at test.util.ComposeMessage.main(ComposeMessage.java:118)，
虽然能够正常把字符串数组result的内容写入到文件中，但是eclipse中这里还是有错误，有没有大神知道为啥啊？谢谢各位了！
java NUllPointerException
package test.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class ComposeMessage {
public static void composeMessage(String dataFileName, String templateFileName,
String outputFileName){
//String tempFile = System.getProperty("user.dir")+"\\src\\test\\util\";
StringBuffer tempStr = new StringBuffer();
String data = new String();
String[] tempData = new String[7];
String[] result = new String[7];
TransRecordManager transRecMan = new TransRecordManager();
//获取文件data.txt的数据,返回并保存在数组temp中
TransRecord[] tempRec = transRecMan.getAll();
//File dataFile = new File(dataFileName);
File templateFile = new File(templateFileName);
BufferedReader reader = null;
FileWriter outputFile = null;
try {
//读取templateFile中的数据，并保存在字符串tempStr中
reader = new BufferedReader(new FileReader(templateFile));
while(null != (data=reader.readLine())){
tempStr.append(data);
}
//获取template中的数据，并保存在tempStr数组中
int iLast = -1;
int count = 0;
int index = tempStr.indexOf("{");
while (index > 0){
tempData[count++] = tempStr.substring(iLast+1, index);
iLast = tempStr.indexOf("}", index+1);
index = tempStr.indexOf("{", iLast+1);
}
//用数组result保存合并后的结果
for(int i = 0; i < tempRec.length; i++){
result[i] = tempData[0] + tempRec[i].getCustomerNumber()
+ tempData[1] + tempRec[i].getCustomerName()
+ tempData[2] + tempRec[i].getJiGou()
+ tempData[3] + tempRec[i].getSex()
+ tempData[4] + tempRec[i].getAccountNumber()
+ tempData[5] + tempRec[i].getHappenTime()
+ tempData[6] + tempRec[i].getAmount();
//System.out.println(result[i]);
}
//System.out.println(result.length);
File file = new File(outputFileName);
try {
outputFile = new FileWriter(file);
for(int i = 0; i < result.length; i++){
outputFile.write(result[i]);
outputFile.write("\r\n");
outputFile.flush();
}
}
catch (IOException e) {
e.printStackTrace();
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e1) {
e1.printStackTrace();
}
finally{
if (null != reader && null != outputFile){
try{
reader.close();
outputFile.close();
}
catch (Exception e){
e.printStackTrace();
}
}
}
}
public static void main(String[] args) throws Exception{
String usageMsg = "请在命令行下按照格式输入："
+ "java ComposeMessage -m dataFileName"
+ "-v templateFileName -o outputFileName";
String dataFileName = System.getProperty("user.dir")
+ "\\src\\test\\util\\data.txt";
//String templateFileName = null;
String templateFileName = System.getProperty("user.dir")+"\\src\\test\\util\\template.txt";
String outputFileName = "c:\\compseMsg.txt";
//参数不符合要求，打印提示信息并退出程序
/*
if(6 != args.length){
System.out.println(usageMsg);
System.exit(1);
}
//从命令行传递的参数获取需要组合的文件名以及合并后保存的文件名
for(int i=0;i<args.length;i++){
if(args[1].equals("-m")||args[1].equals("-M"))
dataFileName = args[i+1];
else if(args[1].equals("-v")||args[1].equals("-V"))
templateFileName = args[i+1];
else if(args[1].equals("-o")||args[1].equals("-O"))
outputFileName = args[i+1];
}
*/
composeMessage(dataFileName,templateFileName,outputFileName);
}
}
