How to sort data in coulmns

[sheed]

Hi,
How do I sort data IN Ascending or Descending order. Following is a sample code. I want to sort on Amount i.e. float OR Value i.e. integer OR Name i.e. String. I am showing data in my app in table and want to provide a functionality if a user clicks on any column header it sorts the whole data according. How can I make sorting work on all my columns. Here is code excerpt that is storing the data:

.....................................
.......................................
Test t = null;
ArrayList a = new ArrayList();

t = new Test();
t.setAmount(23.89);
t.setVal(1);
t.setName("TestName1");
a.add(t);

t = new Test();
t.setAmount(54.00);
t.setVal(2);
t.setName("Name2");
a.add(t);

t = new Test();
t.setAmount(55.89);
t.setVal(3);
t.setName("Doe");
a.add(t);
..........................
.........................

And following is my jsp code:

.....................................
.......................................
ArrayList alist = (ArrayList)session.getAttribute("DataRecords");
 Collections.sort(alist);
 Comparator comp = Collections.reverseOrder();
 Collections.sort(alist,comp);
    ..........................
.........................

Currently I am just sorting on Amount i.e. user clicks the Amount column to sort, how can I make the sort work for other columns i.e. if user clicks on Name column or Value column it sorts all the data.

Any help is appreciated.

Thanks

 

[byam]

You will have to implement your own Comparator to compare Test object based on different "sort-by" column.

 

[sheed]

Here is my class that implementing Comparable. But currently I am just comparing the Amount how can I make to compare Val and Name also.

public class DataSort implements Comparable {
    
    private double cAmount;
    private int cVal;
    private String cName;   
    
    public double getcAmount() 
    {
        return cAmount;
    }

    public void setcAmount(String cAmount)
    {
        this.cAmount = Double.parseDouble(cAmount);
    }
    
    public int getcVal()
    {
        return cVal;
    }

    public void setcVal(String cVal)
    {
        this.cVal = Integer.parseInt(cVal);
    }
    
    public String getcName()
    {
        return cName;
    }

    public void cName(String cName)
    {
        this.cName = cName;
    }
            
    public int compareTo(Object d) throws ClassCastException 
    {
        if (!(d instanceof DataSort))
            throw new ClassCastException("A DataSort object expected.....");
        Double aAmount = new Double(((DataSort) d).getcAmount());
        Double tAmount = new Double(this.cAmount);
        return tAmount.compareTo(aAmount);
    }
}

 

[venur]

Hi,

import java.util.Comparator;

/**
 * User: vreddy
 * Date: Jun 21, 2005
 * Time: 6:00:33 PM
 *
 * @author Venu Reddy 
 */
public class DataSort implements Comparable {

    private double cAmount;
    private int cVal;
    private String cName;

    public double getcAmount() {
        return cAmount;
    }

    public void setcAmount(String cAmount) {
        this.cAmount = Double.parseDouble(cAmount);
    }

    public int getcVal() {
        return cVal;
    }

    public void setcVal(String cVal) {
        this.cVal = Integer.parseInt(cVal);
    }

    public String getcName() {
        return cName;
    }

    public void cName(String cName) {
        this.cName = cName;
    }

    public int compareTo(Object d) throws ClassCastException {
        if (!(d instanceof DataSort))
            throw new ClassCastException("A DataSort object expected.....");
        Double aAmount = new Double(((DataSort) d).getcAmount());
        Double tAmount = new Double(this.cAmount);
        return tAmount.compareTo(aAmount);
    }

    public static Comparator NameComparator = new Comparator() {
        public int compare(Object newTestBean1, Object newTestBean2) {
            String name1 = ((DataSort) newTestBean1).getcName().toUpperCase();
            String name2 = ((DataSort) newTestBean2).getcName().toUpperCase();
            return name1.compareTo(name2);
        }
    };

    public static Comparator ValComparator = new Comparator() {
        public int compare(Object newTestBean1, Object newTestBean2) {
            Integer val1 = new Integer(((DataSort) newTestBean1).getcVal());
            Integer val2 = new Integer(((DataSort) newTestBean1).getcVal());
            return val1.compareTo(val2);
        }
    };

}

Test

import java.util.ArrayList;
import java.util.Iterator;
import java.util.Collections;
import java.util.Comparator;

/**
 * User: vreddy
 * Date: Jun 21, 2005
 * Time: 6:04:33 PM
 *
 * @author Venu Reddy <a href="mailto:venu_dvmr@yahoo.com">Venu Reddy</a>
 */
public class TestBeanTest {

    public static void main(String[] args) {
        ArrayList list = new ArrayList();
        DataSort test = new DataSort();
        test.setcAmount("10");
        test.setcVal("1");
        test.cName("Apple");
        list.add(test);
        test = new DataSort();
        test.setcAmount("10");
        test.setcVal("3");
        test.cName("Cat");
        list.add(test);
        test = new DataSort();
        test.setcAmount("10.12");
        test.setcVal("2");
        test.cName("Boy");
        list.add(test);
        test = new DataSort();
        test.setcAmount("10.15");
        test.setcVal("5");
        test.cName("Zero");
        list.add(test);
        test = new DataSort();
        test.setcAmount("10.14");
        test.setcVal("4");
        test.cName("Dog");
        list.add(test);

        System.out.println("\n");
        System.out.println("*** Orginal List ***");
        printValues(list);
        System.out.println("\n");
        // sort the list
        Collections.sort(list);
        System.out.println("*** Sort By Amount ASC***");
        printValues(list);
        System.out.println("\n");
        System.out.println("*** Reverse Sort By Amount DESC***");
        Comparator comp = Collections.reverseOrder();
        Collections.sort(list,comp);
        printValues(list);

        System.out.println("\n");
        System.out.println("*** Sort By Name ASC***");
        Collections.sort(list, DataSort.NameComparator);
        printValues(list);
        System.out.println("\n");
        System.out.println("*** Reverse Sort By Name DESC***");
        Collections.reverse(list);
        printValues(list);

        System.out.println("\n");
        System.out.println("*** Sort By Val ASC***");
        Collections.sort(list, DataSort.ValComparator);
        printValues(list);
        System.out.println("\n");
        System.out.println("*** Reverse Sort By Val DESC***");
        Collections.reverse(list);
        printValues(list);

    }

    public static void printValues(ArrayList list)
    {
        Iterator iterator = list.iterator();
        while (iterator.hasNext()) {
            DataSort testBean = (DataSort)iterator.next();
            System.out.println("$" + testBean.getcAmount() + ", " + testBean.getcName() + ", " +
                    ""+ testBean.getcVal()+ "");
        }
    }
}

Output

*** Orginal List ***
$10.0, Apple, 1
$10.0, Cat, 3
$10.12, Boy, 2
$10.15, Zero, 5
$10.14, Dog, 4


*** Sort By Amount ASC***
$10.0, Apple, 1
$10.0, Cat, 3
$10.12, Boy, 2
$10.14, Dog, 4
$10.15, Zero, 5


*** Reverse Sort By Amount DESC***
$10.15, Zero, 5
$10.14, Dog, 4
$10.12, Boy, 2
$10.0, Apple, 1
$10.0, Cat, 3


*** Sort By Name ASC***
$10.0, Apple, 1
$10.12, Boy, 2
$10.0, Cat, 3
$10.14, Dog, 4
$10.15, Zero, 5


*** Reverse Sort By Name DESC***
$10.15, Zero, 5
$10.14, Dog, 4
$10.0, Cat, 3
$10.12, Boy, 2
$10.0, Apple, 1


*** Sort By Val ASC***
$10.15, Zero, 5
$10.14, Dog, 4
$10.0, Cat, 3
$10.12, Boy, 2
$10.0, Apple, 1


*** Reverse Sort By Val DESC***
$10.0, Apple, 1
$10.12, Boy, 2
$10.0, Cat, 3
$10.14, Dog, 4
$10.15, Zero, 5

If you are using commons-beanutils.jar and commons-collections.jar in your classpath it will be much simpler and cleaner.

Cheers
Venu

 

[sheed]

Thanks Venu.