apache/hadoop · error · UnsupportedOperationException

xor() is undefined for {}

Error message

xor() is undefined for {}

What it means

Error "xor() is undefined for {}" thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/bloom/CountingBloomFilter.java:265

  public void or(Filter filter) {
    if(filter == null
        || !(filter instanceof CountingBloomFilter)
        || filter.vectorSize != this.vectorSize
        || filter.nbHash != this.nbHash) {
      throw new IllegalArgumentException("filters cannot be or-ed");
    }

    CountingBloomFilter cbf = (CountingBloomFilter)filter;

    int sizeInWords = buckets2words(vectorSize);
    for(int i = 0; i < sizeInWords; i++) {
      this.buckets[i] |= cbf.buckets[i];
    }
  }

  @Override
  public void xor(Filter filter) {
    throw new UnsupportedOperationException("xor() is undefined for "
        + this.getClass().getName());
  }

  @Override
  public String toString() {
    StringBuilder res = new StringBuilder();

    for(int i = 0; i < vectorSize; i++) {
      if(i > 0) {
        res.append(" ");
      }
      
      int wordNum = i >> 4;          // div 16
      int bucketShift = (i & 0x0f) << 2;  // (mod 16) * 4
      
      long bucketMask = 15L << bucketShift;
      long bucketValue = (buckets[wordNum] & bucketMask) >>> bucketShift;
      

View on GitHub (pinned to 2add963021)

Solutions

1. xor() is undefined for CountingBloomFilter ({}): counting filters do not support xor. Restructure the code to avoid xor on counting filters.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/bloom/CountingBloomFilter.java:265 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/655270a4a5232d06. Report an issue: GitHub.