How to display a 2d array of elements

Question

I'd like to display 2d array of floats in a table on a xhtml page using JSF2 and I have no idea how to do that. I tried to find the answer in google but I couldn't. All examples were displaying classes objects and I was not able to make it working with the table.

The sitation is: I have the array of some size - the size of the array depends on entered data: float [][] variables = new float[size1][size2]

After user enters data and pressess button a method is called in the managed bean. The calculation begins and the table is filled with data.

Please tell me how can I display the array.

Please take a look at the following post. http://stackoverflow.com/questions/14217263/rendering-2d-array-without-hdatatable — cubbuk, Jan 29 '13 at 21:37

Aritz · Accepted Answer · 2013-01-30T14:03:52.543

To achieve that you can use c:forEach tag to dinamically buid a h:panelGrid. Just save size2, which is the column number as a property and store all the input numbers in a normal java.util.List. Then you set that size to the h:panelGrid columns attribute and the component will split the rows for you. You can also style the content inside the c:forEach tag, bordering it in order to give it a table behaviour.

<h:form>
    <h:panelGrid columns="#{bean.numberCount}">
        <c:forEach var="num" items="#{bean.numberList}">
            #{number}
        </c:forEach>
    </h:panelGrid>
</h:form>

EDITED

If you want to maintain the original structure but in a List, you can create a List<List<Float>>. That means a List which is composed by List which contains Float Objects. The same as a 2d array.

private List<List<Float>> _Matrix;

public List<List<Float>> get_Matrix() {
    return this._Matrix;
}

/**
 * Constructor for BackingBean.
 */
public BackingBean() {
    this._Matrix = new ArrayList<List<Float>>();
    this._Matrix.add(new ArrayList<Float>());
    this._Matrix.add(new ArrayList<Float>());
    this._Matrix.get(0).add(1.0f);
    this._Matrix.get(0).add(2.0f);
    this._Matrix.get(0).add(3.0f);
    this._Matrix.get(1).add(1.0f);
    this._Matrix.get(1).add(2.0f);
    this._Matrix.get(1).add(3.0f);
}

In the code above I'm constructing the equivalent to a 2d array with 2 rows and values 1.0,2.0 and 3.0 on each row. You can use this code to iterate it over the view:

<h:panelGrid columns="#{backingBean._ColumnNumber}">
        <c:forEach var="row" items="#{backingBean._Matrix}">

            <c:forEach var="value" items="#{row}">

                #{value}
                    </c:forEach>
        </c:forEach>
    </h:panelGrid>

Where #{backingBean._ColumnNumber} will be the length of the first array of the List (supposing all of them have the same length).

Good Luck.

Thans for the answer! The problem is that it is mathematical matrix used for calculations. Rows represent inequalities and collumns number of variables: x1, x2, x3, .. ,xN. The variables are very easy to access in the array and I'm not sure how to map it to a list. Would you be able to write a short example how to use the h:panelGrid and list here? — user2023081, Jan 29 '13 at 22:40

How to display a 2d array of elements

1 Answers1