display a checkbox in a table

[mark smith]

hi

i try to display a check in a jtable

  JTable attributeTable;  
attributeTable = new JTable(new AttributeTableModel());

now my AttributeTableModel class

  public class AttributeTableModel extends AbstractTableModel{

    private List<Attribute> attributes;
    private  String[] COLUMNS= {"Name", "Code", "DataType", "Precision", "Mandatory", "PrimaryKey", "Visible"};
    public AttributeTableModel(){

    }

    public AttributeTableModel(List<Attribute> attributes){
        this.attributes = attributes;
    }

    public void add(Attribute attribute){
        attributes.add(attribute);
    }


    @Override
    public int getRowCount() {
        if(this.attributes!=null)
            return this.attributes.size();
        return 1;
    }

    @Override
    public int getColumnCount() {

        return COLUMNS.length;
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        if(attributes!=null){
        Attribute attribute =  attributes.get(rowIndex);

        switch(columnIndex){
            case 0: return attribute.getName();
        }

        return "1";
        }
        return "";
    }

    public Class getColumnClass(int c) {
        return getValueAt(0, c).getClass();
    }

    public String getColumnName(int col){
        return COLUMNS[col];
    }


    public boolean isCellEditable(int row, int col) {
        return true;
    }

    public void setValueAt(Object value, int row, int col) {

        if(attributes!=null){
            attributes.add((Attribute) value);
            fireTableCellUpdated(row, col);
        }else{
            attributes = new ArrayList();
            Attribute attribute = new Attribute();
            attribute.setName((String) value);
            attributes.add(attribute);
            fireTableCellUpdated(row, col);
        }
    }


}  

my class Attribute

   public class Attribute {

    private String name;
    private String code;
    private DataType dataType;
    private int precision;
    private boolean mandatory;
    private boolean primaryKey;
    private boolean display;
    ....
} 

i was thinking i had only to put boolean field to display the checkbox...

thanks

[Rob Camick]

You getValueAt(...) and setValueAt(...) methods make no sense.

According your the column header you have 7 pieces of information. Therefore your swicth statement needs to handle 7 different cases and return the appropriate piece of data. This is:

if column == 0, return name
if column == 1, return code
if column == 2, return dataType
etc...

[mark smith]

Rob Camick wrote:You getValueAt(...) and setValueAt(...) methods make no sense.

According your the column header you have 7 pieces of information. Therefore your swicth statement needs to handle 7 different cases and return the appropriate piece of data. This is:

if column == 0, return name
if column == 1, return code
if column == 2, return dataType
etc...

ok i fixed it with

 
@Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        if(attributes!=null){

            Attribute attribute =  attributes.get(rowIndex);

            switch(columnIndex){
                case 0: return attribute.getName();
                case 1: return attribute.getCode();
                case 2: return attribute.getDataType();
                case 3: return attribute.getPrecision();
                case 4: return attribute.isMandatory();
                case 5: return attribute.isPrimary();
                case 6: return attribute.isDisplay();

            }
        }
        return "";
    }

public void setValueAt(Object value, int row, int col) {

        if(attributes!=null){

            switch(col){
                case 0: attributes.get(row).setName((String)value);break;
                case 1: attributes.get(row).setCode((String)value);break;
                case 2: attributes.get(row).setDataType((DataType)value);break;
                case 3: attributes.get(row).setPrecision((Integer)value);break;
                case 4: attributes.get(row).setMandatory((Boolean)value);break;
                case 5: attributes.get(row).setPrimary((Boolean)value);break;
                case 6: attributes.get(row).setDisplay((Boolean)value);break;

            }

            fireTableCellUpdated(row, col);
        }else{
            attributes = new ArrayList();
            Attribute attribute = new Attribute();
            attribute.setName((String) value);

            switch(col){
                case 0: attribute.setName((String)value);break;
                case 1: attribute.setCode((String)value);break;
                case 2: attribute.setDataType((DataType)value);break;
                case 3: attribute.setPrecision((Integer)value);break;
                case 4: attribute.setMandatory((Boolean)value);break;
                case 5: attribute.setPrimary((Boolean)value);break;
                case 6: attribute.setDisplay((Boolean)value);break;
            }
            
            attributes.add(attribute);
            fireTableCellUpdated(row, col);
        }
    }
   

i type a value in the grid, i see my value... but when i click outside row..... i get a null pointer exception on

 public Class getColumnClass(int c) {
        return getValueAt(0, c).getClass(); //here
    }   

i put

Object value=this.getValueAt(0,c);
        return (value==null?Object.class:value.getClass());    

to bypass this problem, no sure is the way to go...

i need to go out of the jtable and come back to see the checkbox...

why i don't see a checkbox in the boolean field?

any idea?

[Brian Cole]

mark smith wrote:but when i click outside row..... i get a null pointer exception on

 public Class getColumnClass(int c) {
        return getValueAt(0, c).getClass(); //here
    }   

i put

Object value=this.getValueAt(0,c);
        return (value==null?Object.class:value.getClass());    

to bypass this problem, no sure is the way to go...

Wouldn't it be easier to just do something like this?

public Class getColumnClass(int c) {
  switch(c){
    case 0: return String.class;
    case 1: return String.class;
    case 2: return DataType.class;
    case 3: return Integer.class;
    case 4: return Boolean.class;
    case 5: return Boolean.class;
    case 6: return Boolean.class;
   default: return Object.class;
  }
}

why i don't see a checkbox in the boolean field?

any idea?

Well if it gets a null (or Object.class) instead of Boolean.class when it first calls getColumnClass() then that's what will happen. It won't realize it should use the checkbox renderer.

[mark smith]

Brian Cole wrote:
Wouldn't it be easier to just do something like this?

public Class getColumnClass(int c) {
  switch(c){
    case 0: return String.class;
    case 1: return String.class;
    case 2: return DataType.class;
    case 3: return Integer.class;
    case 4: return Boolean.class;
    case 5: return Boolean.class;
    case 6: return Boolean.class;
   default: return Object.class;
  }
}

i tried that but i get

 java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean   

if i put

  
Object value=this.getValueAt(0,c);
System.out.println(c +" " + value.getClass().toString());
return (value==null?Object.class:value.getClass());  

i get

0 class java.lang.String
1 class java.lang.String
2 class java.lang.String
3 class java.lang.String
4 class java.lang.String
5 class java.lang.String
6 class java.lang.String

i click go out of the jtable and come back... i get a java.lang.NullPointerException at the same place...

[Rob Camick]

Well, don't add String data to your TableModel.

[mark smith]

Rob Camick wrote:Well, don't add String data to your TableModel.

i don't really understand why i could not add string to y my tableModel...

private String name;
    private String code;
    private DataType dataType;
    private int precision;
    private int length;
    private boolean mandatory;
    private boolean primaryKey;
    private boolean display;

so on the web, the code for getColumClass is always very basic...

 public Class getColumnClass(int column) {
    return (getValueAt(0, column).getClass());
  }   

so i don't understand whey that don't work...

[Rob Spoor]

Because check boxes only work for Booleans perhaps? You can add Strings to your TableModel all you want, just not for the check box column.

[santhosh varala kumar]

Rob Prime wrote:Because check boxes only work for Booleans perhaps? You can add Strings to your TableModel all you want, just not for the check box column.

1. In TableModel, getColumnClass() should return Boolean.class insteadof String.class
and the values in that column should be boolean value.

[mark smith]

with that code, that should be ok

 
 public Class getColumnClass(int c) {  
      switch(c){  
        case 0: return String.class;  
        case 1: return String.class;  
        case 2: return DataType.class;  
        case 3: return Integer.class;  
        case 4: return Boolean.class;  
        case 5: return Boolean.class;  
        case 6: return Boolean.class;  
      default: return Object.class;  
     }  
   }  

why that return a string... when i specify a Boolean

that should return the correct type for each column...

one thing i found very very strange

i have put

 Object value=this.getValueAt(0,c);
        return (value==null?Object.class:value.getClass());   

in getColumnClass, when the jtable is displayed, the checkbox is not displayed... but if i click on a string column.... and after a click in a boolean column, i see the check box..

but if i click directely in a boolean column... the checkbox is not displayed...

it's like the type change....

habitually we must use directely getColumnClass or we use a render to display the kind of data in the jtable?

[Brian Cole]

mark smith wrote:
why that return a string... when i specify a Boolean

that should return the correct type for each column...

It returns whatever you tell it to return in the getValueAt(). If you say you will return a Boolean than it expects you to return a Boolean, hence the ClassCastException when you surprise it by returning a String.

If you are expecting the code to somehow convert the the non-Boolean value to a Boolean behind the scenes then you will be disappointed.

[mark smith]

Brian Cole wrote:

mark smith wrote:
why that return a string... when i specify a Boolean

that should return the correct type for each column...

It returns whatever you tell it to return in the getValueAt(). If you say you will return a Boolean than it expects you to return a Boolean, hence the ClassCastException when you surprise it by returning a String.

If you are expecting the code to somehow convert the the non-Boolean value to a Boolean behind the scenes then you will be disappointed.

actually i do:

 @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        if (attributes != null) {

            Attribute attribute = attributes.get(rowIndex);

            switch (columnIndex) {
                case 0:
                    return attribute.getName();
                case 1:
                    return attribute.getCode();
                case 2:
                    return attribute.getDataType();
                case 3:
                    return attribute.getLength();
                case 4:
                    return attribute.getPrecision();
                case 5:
                    return attribute.isMandatory();
                case 6:
                    return attribute.isPrimary();
                case 7:
                    return attribute.isDisplay();
            }
        }   
        return "";
}

the first time the jtable is displayed, attributes is null... so i put empty... so how to put the check box to be able to enable or disabled it...

[Rob Camick]

the first time the jtable is displayed, attributes is null... so i tried to add this code...

Well, attributes should NEVER be null (it may contain 0 rows).

[mark smith]

Rob Camick wrote:

the first time the jtable is displayed, attributes is null... so i tried to add this code...

Well, attributes should NEVER be null (it may contain 0 rows).

hum the first time the jtable is displayed, there are not data... so the list is null
is not correct?

i added this code

   else{
            switch (columnIndex) {
            case 0:
                return "";
            case 1:
                return "";
            case 2:
                return "";
            case 3:
                return "";
            case 4:
                return "";
            case 5:
                return Boolean.FALSE;
            case 6:
                return Boolean.FALSE;
            case 7:
                return Boolean.FALSE;
            default:
                return Object.class;
            }
        }
        return "";
    } 

that work...

[Rob Camick]

i added this code

Well, that is hack fix. You have a fundamental problem with your table. You should design the TableModel such that the attributes ArrayList is NEVER null.

[mark smith]

Rob Camick wrote:

i added this code

Well, that is hack fix. You have a fundamental problem with your table. You should design the TableModel such that the attributes ArrayList is NEVER null.

i can put empty value... but i don't find that very logic... create a empty row only to display a jtable... seem weird

[Brian Cole]

mark smith wrote:
i can put empty value... but i don't find that very logic... create a empty row only to display a jtable... seem weird

Just because the ArrayList is non-null, doesn't mean it contains any rows. After construction, size() returns zero, right?

[Rob Camick]

i can put empty value... but i don't find that very logic... create a empty row only to display a jtable...

You apparently don't understand the concept between an ArrayList being "null" versus it being "empty".

ArrayList list; // this is null

ArrayList list = new ArrayList();  // this is empty

There is no need to add an "empty row" to the model.

To understand what I mean forget about your custom TableModel and do a quick test using the DefaultTableModel. Use:

model = new DefaultTableModel(0, 5);
//model = new DefaultTableModel(1, 5);

to see what the difference is.