Integer nullValue = IntegerConversionUtil.toInteger(null);     // Returns null
Boolean flag = BooleanConversionUtil.toBoolean("true");        // Returns true
Date date = DateConversionUtil.toDate("2023-12-25", "yyyy-MM-dd");

// Primitive conversions with default values
int primitiveInt = IntegerConversionUtil.toPrimitiveInt(value, "0");  // Default to 0 if null
```

### Collection Utilities with Java 21 Support
```java

        int i, j, len, maxLen, dirCount, fileCount, sort;
        String str, name, path, fmt;
        LinkedList sorted;
        ListIterator iter;
        final SimpleDateFormat sdf = new SimpleDateFormat("MM/d/yy h:mm a");
        final GregorianCalendar cal = new GregorianCalendar();

        sdf.setCalendar(cal);

        dirents = dir.listFiles();
        if (LogStream.level > 2) {

	AssertEqual(t, nil, err)
	AssertEqual(t, "integer[]", ct.DatabaseTypeName())
}

type mockMigrator struct {
	gorm.Migrator
}

func (mm mockMigrator) AlterColumn(dst interface{}, field string) error {
	err := mm.Migrator.AlterColumn(dst, field)
	if err != nil {
		return err
	}
	return fmt.Errorf("trigger alter column error, field: %s", field)
}