# CallableStatements and INOUT parameters

INOUT parameters map to an array of the parameter type in the Java programming language. (The method must take an array as its parameter.) This conforms to the recommendations of the SQL standard.

Given the following example:

    CallableStatement call = conn.prepareCall(
        "{CALL doubleMyInt(?)}");
    // for inout parameters, it is good practice to
    // register the outparameter before setting the input value
    call.registerOutParameter(1, Types.INTEGER);
    call.setInt(1,10);
    call.execute();
    int retval = call.getInt(1);

The method doubleIt should take a one-dimensional array of `ints`. Here is sample source code for that method:

    public static void doubleMyInt(int[] i) {
        i[0] *=2;
        /* Derby  returns the first element of the array.*/
    }

Note: The return value is not wrapped in an array even though the parameter to the method is.

The following table shows the parameter array types and return types that correspond to JDBC types.

Table 1. INOUT parameter type correspondence
JDBC Type | Array Type for Method Parameter | Value and Return Type
--- | --- | ---
BIGINT | long[] | long
BINARY | byte[][] | byte[]
BLOB | java.sql.Blob[] | java.sql.Blob
BOOLEAN | boolean[] | boolean
CLOB | java.sql.Clob[] | java.sql.Clob
DATE | java.sql.Date[] | java.sql.Date
DOUBLE | double[] | double
FLOAT | double[] | double
INTEGER | int[] | int
LONGVARBINARY | byte[][] | byte[]
REAL | float[] | float
SMALLINT | short[] | short
TIME | java.sql.Time[] | java.sql.Time
TIMESTAMP | java.sql.Timestamp[] | java.sql.Timestamp
VARBINARY | byte[][] | byte[]
OTHER | yourType[] | yourType
JAVA_OBJECT | yourType[] | yourType

Register the output type of the parameter before executing the call. For INOUT parameters, it is good practice to register the output parameter before setting its input value.

Parent topic: java.sql.CallableStatement interface
Related reference
CallableStatements and OUT Parameters