How to generate the java classes of the database tables

Question

Hi,
I am using Sun One 4 update1 CE for generate java classes of tables from an Oracle database. I have got the database schema file. However, when I right clicked on the database schema file, there is no selection for "Generate Java...".
Besides, when I was trying to use database Schema template from the project tab in the explore window by double click on the project, after following all the procedures of inputing the database url, driver, uername, password, and select the table to generate, the following exception came out:
Tue Jan 28 16:22:28 PST 2003: java.lang.NullPointerException: Posted StackTrace
Annotation: Exception occurred in Request Processor
org.openide.util.RequestProcessor$Holder: Posted StackTrace(task org.netbeans.core.ModuleActions$1@e4b7d3 [-31035, 1, -1])
at org.openide.util.RequestProcessor$Holder.fillInStackTrace(RequestProcessor.java:300)
at java.lang.Throwable.<init>(Throwable.java:195)
at java.lang.Exception.<init>(Exception.java:41)
at org.openide.util.RequestProcessor$Holder.<init>(RequestProcessor.java:280)
at org.openide.util.RequestProcessor$Task.createHolder(RequestProcessor.java:333)
at org.openide.util.RequestProcessor.post(RequestProcessor.java:100)
at org.openide.util.RequestProcessor.post(RequestProcessor.java:73)
at org.netbeans.core.ModuleActions.invokeAction(ModuleActions.java:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.openide.explorer.view.TreeView.invokeAction(TreeView.java:878)
at org.openide.explorer.view.TreeView$PopupSupport.mouseClicked(TreeView.java:958)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:208)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:207)
at java.awt.Component.processMouseEvent(Component.java:5096)
at java.awt.Component.processEvent(Component.java:4890)
at java.awt.Container.processEvent(Container.java:1566)
at java.awt.Component.dispatchEventImpl(Component.java:3598)
at java.awt.Container.dispatchEventImpl(Container.java:1623)
at java.awt.Component.dispatchEvent(Component.java:3439)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3450)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3174)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3095)
at java.awt.Container.dispatchEventImpl(Container.java:1609)
at java.awt.Window.dispatchEventImpl(Window.java:1585)
at java.awt.Component.dispatchEvent(Component.java:3439)
[catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
Tue Jan 28 16:22:28 PST 2003: java.lang.NullPointerException: <no message>
java.lang.NullPointerException
at org.netbeans.modules.projects.ProjectDataObject.add(ProjectDataObject.java:204)
at org.netbeans.modules.projects.AddNewAction.performAction(AddNewAction.java:88)
at org.openide.util.actions.NodeAction.actionPerformed(NodeAction.java:167)
at org.netbeans.core.ModuleActions$1.run(ModuleActions.java:105)
at org.openide.util.Task.run(Task.java:152)
[catch] at org.openide.util.RequestProcessor$ProcessorThread.run(RequestProcessor.java:622)
Any suggestions to the solution of these problems are greatly appreciated. Thanks.
Yi-Xiong

Answer 1

you also could use this to generate java beans out of database tables:
     * Convert SQL type code to corresponding Java class.
     * @param sqlType One of java.sql.Types.xxx.
     * @return Class that corresponds to the given type.
    public static Class toClass(int sqlType) {
        Class result = null;
        switch (sqlType) {
        case Types.BIGINT :
        case Types.INTEGER :
        case Types.SMALLINT :
        case Types.TINYINT :
            result = Integer.class;
            break;
        case Types.BIT :
        case Types.BOOLEAN :
            result = Boolean.class;
            break;
        case Types.CHAR :
            result = Character.class;
            break;
        case Types.DATE :
        case Types.TIMESTAMP :
            result = java.util.Date.class;
            break;
        case Types.DECIMAL :
        case Types.DOUBLE :
        case Types.FLOAT :
            result = BigDecimal.class;
            break;
        case Types.NULL :
            result = null;
            break;
        case Types.LONGVARCHAR :
        case Types.VARCHAR :
        default :
            result = String.class;
            break;
        return result;
    }//toClass()
     * Create a Java bean (source file) to map a database table. The class name is the table name, the bean
     * properties are the table columns. Each column will result in a property with a corresponding set() and
     * get() method.
     * @param connection Database connection to load table from.
     * @param tableName Name of table to create the bean for.
     * @param packageName Name of package for Java class.
     * @param className Name of Java class to create.
     * @param superClass Optional name of super class.
     * @return Java source of container class.
     * @throws SQLException, IOException
     * @see <a href="http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html">Data Access Object </a>
    public static String getTableBean(Connection connection, String tableName, String packageName, String className, String superClass)
            throws SQLException, IOException {
        String result = null;
        if (connection != null && tableName != null) {
            //read table columns:
            DatabaseMetaData dmd = connection.getMetaData();
            ResultSet resultSet = dmd.getColumns(null, "%", tableName, null);
            Properties props = new Properties();
            if (resultSet != null) {
                while (resultSet.next()) { //for each table
                    String name = resultSet.getString("COLUMN_NAME");
                    int type = resultSet.getInt("DATA_TYPE");
                    props.setProperty(name, ""+type);
                }//next table
            }//else: resultSet unavailable
            Set imports = new HashSet();
            StringBuffer sb1 = new StringBuffer(); //fields
            StringBuffer sb2 = new StringBuffer(); //methods
            StringBuffer sb3 = new StringBuffer(); //toString()
            Enumeration enum = props.keys();
            while (enum.hasMoreElements()) {
                String columnName = (String) enum.nextElement();
                //change first character of column name to lower case:
                String fieldName = columnName.substring(0, 1).toLowerCase() + columnName.substring(1);
                //datat type:
                String stype = props.getProperty(columnName, ""+Types.VARCHAR);
                int type = (new Integer(stype)).intValue();
                Class javaClass = toClass(type);
                String typeName = "String"; //default
                if (javaClass != null) {
                    String javaClassName = javaClass.getName();
                    int lastDot = javaClassName.lastIndexOf('.');
                    if (lastDot >= 0) {
                        typeName = javaClassName.substring(lastDot + 1);
                    if (!javaClassName.startsWith("java.lang.")) {
                        imports.add(javaClassName);
                //field:
                sb1.append("    /** ");
                sb1.append(columnName);
                sb1.append(" */\n");
                sb1.append("    private ");
                sb1.append(typeName);
                sb1.append(" ");
                sb1.append(fieldName);
                sb1.append(" = null;\n");
                //toString() method:
                sb3.append("        sb.append(\",");
                sb3.append(fieldName);
                sb3.append("=\");\n");
                sb3.append("        sb.append(");
                sb3.append(fieldName);
                sb3.append(");\n");
                //set method:
                sb2.append("    /**\n");
                sb2.append("     * Set ");
                sb2.append(columnName);
                sb2.append(".\n     *\n     * @param value ");
                sb2.append(columnName);
                sb2.append(" to set.\n");
                sb2.append("     */\n");
                sb2.append("    public void set");
                sb2.append(columnName);
                sb2.append("(");
                sb2.append(typeName);
                sb2.append(" value) {\n        ");
                sb2.append(fieldName);
                sb2.append(" = value;\n    }\n\n");
                //get method:
                sb2.append("    /**\n");
                sb2.append("     * Get ");
                sb2.append(columnName);
                sb2.append(".\n     *\n     * @return ");
                sb2.append(columnName);
                sb2.append(".\n     */\n");
                sb2.append("    public ");
                sb2.append(typeName);
                sb2.append(" get");
                sb2.append(columnName);
                sb2.append("() {\n");
                sb2.append("        return ");
                sb2.append(fieldName);
                sb2.append(";\n    }\n\n");
            }//next column
            //build class source code:
            StringBuffer sb = new StringBuffer();
            sb.append("/* $Header: /data/iComps/icf/prg/java/src/de/icomps/sql/JDBCUtils.java 9     24.10.03 14:25 Hilpert $ */\n");
            sb.append("package ");
            sb.append(packageName);
            sb.append(";\n\n");
            //import statements:
            Iterator iterator = imports.iterator();
            while (iterator.hasNext()) {
                String jcn = (String) iterator.next();
                sb.append("import ");
                sb.append(jcn);
                sb.append(";\n");
            if (imports.size() > 0) {
                sb.append("\n");
            //class:
            sb.append("/**\n");
            sb.append(" * Container class to store data of one record (row) of table '"+tableName+"'.\n");
            sb.append(" *\n");
            sb.append(" * @version $Revision: 9 $ ($Date: 24.10.03 14:25 $)\n");
            sb.append(" * @author $Author: Hilpert $\n");
            sb.append(" */\n");
            sb.append("public class ");
            sb.append(className);
            if (superClass != null) {
                sb.append(" extends ");
                sb.append(superClass);
            sb.append(" {\n\n");
            //fields:
            sb.append(sb1.toString());
            //methods:
            sb.append("\n\n");
            sb.append(sb2.toString()); //methods
            //overwrite toString() method:
            sb.append("    /**\n");
            sb.append("     * Overwrite super.\n");
            sb.append("     *\n     * @return String representation of the object.\n");
            sb.append("     */\n");
            sb.append("    public String toString() {\n");
            sb.append("        StringBuffer sb = new StringBuffer(super.toString());\n\n");
            sb.append(sb3.toString());
            sb.append("\n        return sb.toString();\n");
            sb.append("    }\n\n");
            sb.append("}//"+className);
            result = sb.toString();
        }//else: input unavailable
        return result;
    }//getTableBean()