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public interface Writable
A serializable object which implements a simple, efficient, serialization
protocol, based on DataInput and DataOutput.
Any key or value type in the Hadoop Map-Reduce
framework implements this interface.
Implementations typically implement a static read(DataInput)
method which constructs a new instance, calls readFields(DataInput)
and returns the instance.
Example:
public class MyWritable implements Writable {
// Some data
private int counter;
private long timestamp;
public void write(DataOutput out) throws IOException {
out.writeInt(counter);
out.writeLong(timestamp);
}
public void readFields(DataInput in) throws IOException {
counter = in.readInt();
timestamp = in.readLong();
}
public static MyWritable read(DataInput in) throws IOException {
MyWritable w = new MyWritable();
w.readFields(in);
return w;
}
}
| Method Summary | |
|---|---|
void |
readFields(DataInput in)
Deserialize the fields of this object from in. |
void |
write(DataOutput out)
Serialize the fields of this object to out. |
| Method Detail |
|---|
void write(DataOutput out)
throws IOException
out.
out - DataOuput to serialize this object into.
IOException
void readFields(DataInput in)
throws IOException
in.
For efficiency, implementations should attempt to re-use storage in the existing object where possible.
in - DataInput to deseriablize this object from.
IOException
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