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Retrieving Data from a ResultSet
It’s a simple matter getting the data from the Resultset object, as illustrated in Listing 4.
Listing 4 Looping Through a ResultSet object
while (rs.next()) { for (int loop = 1; loop <= numColumns; loop++) { System.out.println("Column value: " + String)(rs.getString(loop))); } }
In Listing 4, I’m being a little lazy because I assume that all the items in the rs object are of type String.
The type of program output you should expect to see is illustrated in Listing 5.
Listing 5 The complete program output
EmbeddedSchema starting in embedded mode. Loaded the appropriate driver. Connected to and created database derbyDB Created table ASSEMBLY_TABLE Created table COMPONENT_TABLE Column value: COMPUTER Column value: VENDOR1 Column value: ENTRY_LEVEL Column value: 3 Column value: COMPUTER1 Column value: VENDOR2 Column value: ENTRY_LEVEL Column value: 2 Column value: 1 Column value: SYSTEM_UNIT_VENDOR1 Column value: MONITOR_VENDOR1 Column value: KEYBOARD_VENDOR3 Column value: 2 Column value: SYSTEM_UNIT_VENDOR2 Column value: MONITOR_VENDOR3 Column value: KEYBOARD_VENDOR2 Dropped table ASSEMBLY_TABLE Dropped table COMPONENT_TABLE Closed result set and statement Committed transaction and closed connection Database shut down normally
It is possible to extract type-specific data from a ResultSet (for example, by using the method rs.getInt(). The way I did it here is to just assume that all columns are Strings.
This can make it a little easier to retrieve data because the only requirement is to know in advance the number of columns to expect.