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## org.springframework.jdbc.core
Class RowCountCallbackHandler

    java.lang.Object
      org.springframework.jdbc.core.RowCountCallbackHandler

All Implemented Interfaces:
  RowCallbackHandler

    public class RowCountCallbackHandler

extends Object
implements RowCallbackHandler

Implementation of RowCallbackHandler. Convenient superclass for callback handlers. An instance can only be used once.

We can either use this on its own (for example, in a test case, to ensure that our result sets have valid dimensions), or use it as a superclass for callback handlers that actually do something, and will benefit from the dimension information it provides.

A usage example with JdbcTemplate:

    JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);  // reusable object

     RowCountCallbackHandler countCallback = new RowCountCallbackHandler();  // not reusable
     jdbcTemplate.query("select * from user", countCallback);
     int rowCount = countCallback.getRowCount();

Since:
  May 3, 2001
Author:
  Rod Johnson

Constructor Summary
`RowCountCallbackHandler()`

Method Summary
`int` | `getColumnCount()` Return the number of columns in this result set.
`String[]` | `getColumnNames()` Return the names of the columns.
`int[]` | `getColumnTypes()` Return the types of the columns as java.sql.Types constants Valid after processRow is invoked the first time.
`int` | `getRowCount()` Return the row count of this ResultSet Only valid after processing is complete
`void` | `processRow(ResultSet rs)` Implementation of ResultSetCallbackHandler.
`protected void` | `processRow(ResultSet rs, int rowNum)` Subclasses may override this to perform custom extraction or processing.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### RowCountCallbackHandler

    public RowCountCallbackHandler()

Method Detail

### processRow

    public final void processRow(ResultSet rs)
                          throws SQLException

  Implementation of ResultSetCallbackHandler. Work out column size if this is the first row, otherwise just count rows.

  Subclasses can perform custom extraction or processing by overriding the `processRow(ResultSet, int)` method.

  Specified by:
    `processRow` in interface `RowCallbackHandler`
  Parameters:
    `rs` - the ResultSet to process (pre-initialized for the current row)
  Throws:
    `SQLException` - if a SQLException is encountered getting column values (that is, there's no need to catch SQLException)
  See Also:
    `processRow(java.sql.ResultSet, int)`

### processRow

    protected void processRow(ResultSet rs,
                              int rowNum)
                       throws SQLException

  Subclasses may override this to perform custom extraction or processing. This class's implementation does nothing.

  Parameters:
    `rs` - ResultSet to extract data from. This method is invoked for each row
    `rowNum` - number of the current row (starting from 0)
  Throws:
    `SQLException`

### getColumnTypes

    public final int[] getColumnTypes()

  Return the types of the columns as java.sql.Types constants Valid after processRow is invoked the first time.

  Returns:
    the types of the columns as java.sql.Types constants. Indexed from 0 to n-1.

### getColumnNames

    public final String[] getColumnNames()

  Return the names of the columns. Valid after processRow is invoked the first time.

  Returns:
    the names of the columns. Indexed from 0 to n-1.

### getRowCount

    public final int getRowCount()

  Return the row count of this ResultSet Only valid after processing is complete

  Returns:
    the number of rows in this ResultSet

### getColumnCount

    public final int getColumnCount()

  Return the number of columns in this result set. Valid once we've seen the first row, so subclasses can use it during processing

  Returns:
    the number of columns in this result set

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