Is it possible to generate reports dynamically using Jasper Reports without generating a jasper for each report?

I have to generate reports based on various parameters which would be provided dynamically. In certain contexts, the parameters may be null. For example, from the table Person with id, name, age, sex and maritalStatus as fields, I would have to generate reports on married male persons of age 30. Some other times, it may be required to get married female without considering age. If I use the same jasper for both these cases, the age constraint will be null in second case. Is there any way to manage this condition?

Also, is it possible to dynamically specify which all fields should be produced in the report?

The sample of using the JasperReport API for generating report dynamically:

    //JasperDesign
    JasperDesign jasperDesign = new JasperDesign();
    jasperDesign.setName("The dynamically generated report");
    jasperDesign.setPageWidth(595);
    jasperDesign.setPageHeight(842);
    jasperDesign.setColumnWidth(515);
    jasperDesign.setColumnSpacing(0);
    jasperDesign.setLeftMargin(40);
    jasperDesign.setRightMargin(40);
    jasperDesign.setTopMargin(50);
    jasperDesign.setBottomMargin(50);

    //Query
    JRDesignQuery query = new JRDesignQuery();
    query.setText("SELECT * FROM Address $P!{OrderByClause}");
    jasperDesign.setQuery(query);

    //Fields
    JRDesignField field = new JRDesignField();
    field.setName("Id");
    field.setValueClass(java.lang.Integer.class);
    jasperDesign.addField(field);

    field = new JRDesignField();
    field.setName("FirstName");
    field.setValueClass(java.lang.String.class);
    jasperDesign.addField(field);

    field = new JRDesignField();
    field.setName("LastName");
    field.setValueClass(java.lang.String.class);
    jasperDesign.addField(field);

    //some code

    //Detail
    band = new JRDesignBand();
    band.setHeight(40);

    JRDesignStaticText staticText = new JRDesignStaticText();
    staticText.setX(0);
    staticText.setY(0);
    staticText.setWidth(60);
    staticText.setHeight(20);
    staticText.setMode(ModeEnum.OPAQUE);
    staticText.setHorizontalAlignment(HorizontalAlignEnum.LEFT);
    staticText.setStyle(boldStyle);
    staticText.setText("ID: ");
    staticText.getLineBox().getLeftPen().setLineWidth(1);
    staticText.getLineBox().getTopPen().setLineWidth(1);
    staticText.getLineBox().setLeftPadding(10);
    band.addElement(staticText);

    textField = new JRDesignTextField();
    textField.setX(60);
    textField.setY(0);
    textField.setWidth(200);
    textField.setHeight(20);
    textField.setHorizontalAlignment(HorizontalAlignEnum.LEFT);
    textField.setStyle(normalStyle);
    expression = new JRDesignExpression();
    expression.setValueClass(java.lang.Integer.class);
    expression.setText("$F{Id}");
    textField.setExpression(expression);
    textField.getLineBox().getTopPen().setLineWidth(1);
    textField.getLineBox().getRightPen().setLineWidth(1);
    textField.getLineBox().setLeftPadding(10);
    band.addElement(textField);

    staticText = new JRDesignStaticText();
    staticText.setX(0);
    staticText.setY(20);
    staticText.setWidth(60);
    staticText.setHeight(20);
    staticText.setMode(ModeEnum.OPAQUE);
    staticText.setHorizontalAlignment(HorizontalAlignEnum.LEFT);
    staticText.setStyle(boldStyle);
    staticText.setText("Name: ");
    staticText.getLineBox().getLeftPen().setLineWidth(1);
    staticText.getLineBox().getBottomPen().setLineWidth(1);
    staticText.getLineBox().setLeftPadding(10);
    band.addElement(staticText);

    textField = new JRDesignTextField();
    textField.setStretchWithOverflow(true);
    textField.setX(60);
    textField.setY(20);
    textField.setWidth(200);
    textField.setHeight(20);
    textField.setPositionType(PositionTypeEnum.FLOAT);
    textField.setStyle(normalStyle);
    expression = new JRDesignExpression();
    expression.setValueClass(java.lang.String.class);
    expression.setText("$F{FirstName} + \" \" + $F{LastName}");
    textField.setExpression(expression);
    textField.getLineBox().getRightPen().setLineWidth(1);
    textField.getLineBox().getBottomPen().setLineWidth(1);
    textField.getLineBox().setLeftPadding(10);
    band.addElement(textField);

    ((JRDesignSection) jasperDesign.getDetailSection()).addBand(band);

You can find more samples in %JasperReportsFolder%/demo/samples folder from the JasperReports distribution package.