OpenJDK 27 · javax.sql.rowset.Predicate · APIdia, the JavaDoc alternative

The standard interface that provides the framework for all FilteredRowSet objects to describe their filters.

1.0 Background

The Predicate interface is a standard interface that applications can implement to define the filter they wish to apply to a a FilteredRowSet object. A FilteredRowSet object consumes implementations of this interface and enforces the constraints defined in the implementation of the method evaluate. A FilteredRowSet object enforces the filter constraints in a bi-directional manner: It outputs only rows that are within the constraints of the filter; and conversely, it inserts, modifies, or updates only rows that are within the constraints of the filter.

2.0 Implementation Guidelines

In order to supply a predicate for the FilteredRowSet. this interface must be implemented. At this time, the JDBC RowSet Implementations (JSR-114) does not specify any standard filters definitions. By specifying a standard means and mechanism for a range of filters to be defined and deployed with both the reference and vendor implementations of the FilteredRowSet interface, this allows for a flexible and application motivated implementations of Predicate to emerge.

A sample implementation would look something like this:

public class Range implements Predicate {

      private int[] lo;
      private int[] hi;
      private int[] idx;

      public Range(int[] lo, int[] hi, int[] idx) {
         this.lo = lo;
         this.hi = hi;
         this.idx = idx;
      }

     public boolean evaluate(RowSet rs) {

         // Check the present row determine if it lies
         // within the filtering criteria.

         for (int i = 0; i < idx.length; i++) {
            int value;
            try {
                value = (Integer) rs.getObject(idx[i]);
            } catch (SQLException ex) {
                Logger.getLogger(Range.class.getName()).log(Level.SEVERE, null, ex);
                return false;
            }

            if (value < lo[i] && value > hi[i]) {
                // outside of filter constraints
                return false;
            }
        }
        // Within filter constraints
       return true;
     }
  }

The example above implements a simple range predicate. Note, that implementations should but are not required to provide String and integer index based constructors to provide for JDBC RowSet Implementation applications that use both column identification conventions.

Method Summary

Modifier and Type	Method and Description
public boolean	Returns: `true` if there are more rows in the filter; `false` otherwise evaluate(RowSet The `RowSet` to be evaluated rs) This method is typically called a `FilteredRowSet` object internal methods (not public) that control the `RowSet` object's cursor moving from row to the next.
public boolean	Returns: `true` if row value lies within the filter; `false` otherwise evaluate(Object An `Object` value which needs to be checked, whether it can be part of this `FilterRowSet` object. value, int a `int` object that must match the SQL index of a column in this `RowSet` object. This must have been passed to `Predicate` as one of the columns for filtering while initializing a `Predicate` column) This method is called by a `FilteredRowSet` object to check whether the value lies between the filtering criterion (or criteria if multiple constraints exist) set using the `setFilter()` method.
public boolean	Returns: `true` if value lies within the filter; `false` otherwise evaluate(Object An `Object` value which needs to be checked, whether it can be part of this `FilterRowSet`. value, String a `String` object that must match the SQL name of a column in this `RowSet`, ignoring case. This must have been passed to `Predicate` as one of the columns for filtering while initializing a `Predicate` columnName) This method is called by the `FilteredRowSet` object to check whether the value lies between the filtering criteria set using the setFilter method.

Method Detail

evaluate back to summary

evaluate	back to summary
public boolean evaluate(RowSet rs) This method is typically called a `FilteredRowSet` object internal methods (not public) that control the `RowSet` object's cursor moving from row to the next. In addition, if this internal method moves the cursor onto a row that has been deleted, the internal method will continue to ove the cursor until a valid row is found. Parameters rs:RowSet The `RowSet` to be evaluated Returns:boolean `true` if there are more rows in the filter; `false` otherwise

public boolean evaluate(RowSet rs)

This method is typically called a FilteredRowSet object internal methods (not public) that control the RowSet object's cursor moving from row to the next. In addition, if this internal method moves the cursor onto a row that has been deleted, the internal method will continue to ove the cursor until a valid row is found.

Parameters

rs:RowSet: The RowSet to be evaluated

Returns:boolean

true if there are more rows in the filter; false otherwise

evaluate back to summary

evaluate	back to summary
public boolean evaluate(Object value, int column) throws SQLException This method is called by a `FilteredRowSet` object to check whether the value lies between the filtering criterion (or criteria if multiple constraints exist) set using the `setFilter()` method. The `FilteredRowSet` object will use this method internally while inserting new rows to a `FilteredRowSet` instance. Parameters value:Object An `Object` value which needs to be checked, whether it can be part of this `FilterRowSet` object. column:int a `int` object that must match the SQL index of a column in this `RowSet` object. This must have been passed to `Predicate` as one of the columns for filtering while initializing a `Predicate` Returns:boolean `true` if row value lies within the filter; `false` otherwise Exceptions SQLException: if the column is not part of filtering criteria

public boolean evaluate(Object value, int column) throws SQLException

This method is called by a FilteredRowSet object to check whether the value lies between the filtering criterion (or criteria if multiple constraints exist) set using the setFilter() method.

The FilteredRowSet object will use this method internally while inserting new rows to a FilteredRowSet instance.

Parameters

value:Object: An Object value which needs to be checked, whether it can be part of this FilterRowSet object.
column:int: a int object that must match the SQL index of a column in this RowSet object. This must have been passed to Predicate as one of the columns for filtering while initializing a Predicate

Returns:boolean

true if row value lies within the filter; false otherwise

Exceptions

SQLException:: if the column is not part of filtering criteria

evaluate back to summary

evaluate	back to summary
public boolean evaluate(Object value, String columnName) throws SQLException This method is called by the `FilteredRowSet` object to check whether the value lies between the filtering criteria set using the setFilter method. The `FilteredRowSet` object will use this method internally while inserting new rows to a `FilteredRowSet` instance. Parameters value:Object An `Object` value which needs to be checked, whether it can be part of this `FilterRowSet`. columnName:String a `String` object that must match the SQL name of a column in this `RowSet`, ignoring case. This must have been passed to `Predicate` as one of the columns for filtering while initializing a `Predicate` Returns:boolean `true` if value lies within the filter; `false` otherwise Exceptions SQLException: if the column is not part of filtering criteria

public boolean evaluate(Object value, String columnName) throws SQLException

This method is called by the FilteredRowSet object to check whether the value lies between the filtering criteria set using the setFilter method.

The FilteredRowSet object will use this method internally while inserting new rows to a FilteredRowSet instance.

Parameters

value:Object: An Object value which needs to be checked, whether it can be part of this FilterRowSet.
columnName:String: a String object that must match the SQL name of a column in this RowSet, ignoring case. This must have been passed to Predicate as one of the columns for filtering while initializing a Predicate

Returns:boolean

true if value lies within the filter; false otherwise

Exceptions

SQLException:: if the column is not part of filtering criteria

public Interface Predicate

1.0 Background

2.0 Implementation Guidelines

Method Summary

Method Detail