Question

我正在尝试编写Java MapReduce代码并不断收到错误：

Error: java.lang.NumberFormatException: For input string: "time"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Long.parseLong(Long.java:589)
at java.lang.Long.parseLong(Long.java:631)
at TokenizerMapper.map(Unknown Source)
at TokenizerMapper.map(Unknown Source)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:793)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:164)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1917)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)

有问题的映射器代码如下

    public class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> {
    private final IntWritable one = new IntWritable(1);
    private Text data = new Text();
    String[] transactionData = new String[5];

    public void map(Object key, Text value, Context context) throws IOException, InterruptedException {


        StringTokenizer itr = new StringTokenizer(value.toString(), ",");


        while (itr.hasMoreTokens()) {

            for (int i = 0; i < 5; i++) {
                transactionData[i] = itr.nextToken();
            }


            Long timestamp = Long.parseLong(transactionData[2]);
            Instant instant = Instant.ofEpochSecond(timestamp);
            LocalDateTime ldt = LocalDateTime.ofInstant(instant, ZoneId.of("GMT"));
            int year = ldt.getYear(); //e.g 2009
            Month month = ldt.getMonth(); //e.g JANUARY

            String time = month.toString() + ":" + Integer.toString(year);

            data.set(time);

            context.write(data, one);
        }
    }
}

应该在csv数据集的每一行中取第3个值，该值是一个数字，将其转换为字符串，将其转换为long，然后使用long查找月份和年份。

我要去哪里错了？谢谢。

编辑//示例条目：

0e3e2357e806b6cdb1f70b54c3a3a17b6714ee1f0e68bebb44a74b1efd512098,00000000839a8e6886ab5951d76f411475428afc90947ee320161bbf18eb6048,1231469665,1,1

Answer 1

如果问题是标题，则只需替换导致问题的行：

Long timestamp = Long.parseLong(transactionData[2]);

与

Long timestamp = 0L;
try {
    timestamp = Long.parseLong(transactionData[2]);
} catch (NumberFormatException e) {
    return;
}

因此，如果该值无效，该方法将终止而不会崩溃。

错误：java.lang.NumberFormatException：对于输入字符串：“ time”

1 个答案: