hadoop - Java MapReduce：如何在 Hadoop 输出中存储 LONG 列表

Question

我有一个 MapReduce Java 程序，它以字符串形式输出一个数字列表作为最终输出。但是编号比较长，占用空间太大。我想将每个数字转换为 Long 并存储。我怎样才能做到这一点？

Answer 1

ArrayWritable可以扩展为

public class LongArrayWritable extends ArrayWritable {
    public LongArrayWritable() {
        super(Text.class);
    }

    public LongArrayWritable(LongWritable[] values) {
        super(LongWritable.class, values);
    }
}

此外，可以将 String 转换为LongWritable为

String s = "123456";
new LongWritable((new Long(s)).longValue());