spark udaf返回值为null导致空指针异常如何处理?
时间: 2024-03-01 15:51:09 浏览: 27
出现空指针异常的原因可能是UDAF的实现中没有对空值进行处理。可以在UDAF中增加对空值的处理逻辑,例如:
```
public class MyUDAF extends UserDefinedAggregateFunction {
// 定义聚合数据的数据类型和结果类型
private StructType inputSchema = DataTypes.createStructType(Arrays.asList(
DataTypes.createStructField("inputCol", DataTypes.DoubleType, true)
));
private StructType bufferSchema = DataTypes.createStructType(Arrays.asList(
DataTypes.createStructField("sum", DataTypes.DoubleType, true),
DataTypes.createStructField("count", DataTypes.LongType, true)
));
private DataType dataType = DataTypes.DoubleType;
private boolean deterministic = true;
@Override
public StructType inputSchema() {
return inputSchema;
}
@Override
public StructType bufferSchema() {
return bufferSchema;
}
@Override
public DataType dataType() {
return dataType;
}
@Override
public boolean deterministic() {
return deterministic;
}
@Override
public void initialize(MutableAggregationBuffer buffer) {
buffer.update(0, 0.0);
buffer.update(1, 0L);
}
@Override
public void update(MutableAggregationBuffer buffer, Row input) {
if (!input.isNullAt(0)) {
double sum = buffer.getDouble(0) + input.getDouble(0);
long count = buffer.getLong(1) + 1;
buffer.update(0, sum);
buffer.update(1, count);
}
}
@Override
public void merge(MutableAggregationBuffer buffer1, Row buffer2) {
double sum = buffer1.getDouble(0) + buffer2.getDouble(0);
long count = buffer1.getLong(1) + buffer2.getLong(1);
buffer1.update(0, sum);
buffer1.update(1, count);
}
@Override
public Object evaluate(Row buffer) {
if (buffer.isNullAt(1) || buffer.getLong(1) == 0) {
return null;
} else {
return buffer.getDouble(0) / buffer.getLong(1);
}
}
}
```
在`evaluate`方法中,增加了对空值的判断,如果计数器为0或者空值,则返回`null`。这样可以避免出现空指针异常。