This example demonstrate how to use PropertyUtils.setMappedProperty() method to modify a Map typed property value of a bean. To set the property we need to pass bean instance, property name, map key and map value to PropertyUtils.setMappedProperty() method.

package org.kodejava.example.commons.beanutils;

import org.apache.commons.beanutils.PropertyUtils;

import java.util.HashMap;
import java.util.Map;

public class PropertySetMappedExample {

    public static void main(String[] args) {
        //
        // Create an instance of Recording bean.
        //
        Recording recording = new Recording();
        recording.setId(1L);
        recording.setTitle("Introduction");

        //
        // Create a map to hold recording tracks.
        //
        Map tracks = new HashMap<>();
        tracks.put("track-one", new Track());
        tracks.put("track-two", new Track());
        tracks.put("track-three", new Track());
        recording.setMapTracks(tracks);

        try {
            //
            // We add another tracks to the recording track using
            // a PropertyUtils.setMappedProperty() method.
            //
            PropertyUtils.setMappedProperty(recording, "mapTracks", "track-four", new Track());
            PropertyUtils.setMappedProperty(recording, "mapTracks", "track-five", new Track());
        } catch (Exception e) {
            e.printStackTrace();
        }

        tracks = recording.getMapTracks();
        System.out.println("New Track Numbers: " + tracks.size());
        for (String key : tracks.keySet()) {
            System.out.println(key + " = " + tracks.get(key));
        }
    }
}

In this example we display how to set the value of an indexed property. In the code below we modified the value of an array type. We’ll change the second colors of MyBean‘s colors property.

We do it in the same way as using the PropertyUtils.setSimpleProperty method. For indexed property we use the PropertyUtils.setIndexedProperty method and passes four arguments, they are the instance of bean to be manipulated, the indexed property name, the index to be changes and the finally the new value.

package org.kodejava.example.commons.beanutils;

import org.apache.commons.beanutils.PropertyUtils;

import java.util.Arrays;

public class PropertySetIndexedExample {
    public static void main(String[] args) {
        String[] colors = new String[]{"red", "green", "blue"};

        MyBean myBean = new MyBean();
        myBean.setColors(colors);
        System.out.println("Colors = " + Arrays.toString(myBean.getColors()));

        try {
            PropertyUtils.setIndexedProperty(myBean, "colors", 1, "orange");
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.out.println("Colors = " + Arrays.toString(myBean.getColors()));
    }
}

package org.kodejava.example.commons.beanutils;

public class MyBean {
    private String[] colors;

    public void setColors(String[] colors) {
        this.colors = colors;
    }

    public String[] getColors() {
        return colors;
    }
}

The output of this code is:

Colors = [red, green, blue]
Colors = [red, orange, blue]

The Commons BeanUtils component provides a class called PropertyUtils that supplies method for manipulating a bean such as our Track class below. For this demo we use a Track class that have a property called id, title and duration.

To set the value of a bean we can use the PropertyUtils.setProperty() method. This method ask for the bean instance whose property value to be set, the property name and the value.

package org.kodejava.example.commons.beanutils;

import org.apache.commons.beanutils.PropertyUtils;

public class PropertySetExample {
    public static void main(String[] args) {
        Track track = new Track();
        try {
            PropertyUtils.setProperty(track, "id", 10L);
            PropertyUtils.setProperty(track, "title", "Hey Jude");
            PropertyUtils.setProperty(track, "duration", 180);
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.out.println("Track = " + track);
    }
}

Some exceptions could be thrown by this method, so we need to handle the IllegalAccessException, InvocationAccessException and NoSuchMethodException. To make the code simple we will just catch it as java.lang.Exception.

These exception could happen if we don’t have access to the property, or the bean’s accessor throws an exception or if the method we tried to manipulate doesn’t exist.

In this example you’ll see how to read mapped property value of a bean. We use PropertyUtils.getMappedProperty() method the read the mapped property of the Recording object that consist of Track objects.

package org.kodejava.example.commons.beanutils;

import org.apache.commons.beanutils.PropertyUtils;

import java.util.HashMap;
import java.util.Map;

public class ReadMapProperty {
    public static void main(String[] args) {
        Recording recording = new Recording();
        recording.setTitle("Please Please Me");

        Track track1 = new Track();
        track1.setTitle("I Saw Her Standing There");

        Track track2 = new Track();
        track2.setTitle("Misery");

        Map tracks = new HashMap<>();
        tracks.put("Track One", track1);
        tracks.put("Track Two", track2);

        recording.setMapTracks(tracks);

        try {
            Track track = (Track) PropertyUtils.getMappedProperty(recording, "mapTracks(Track One)");
            System.out.println("track.getTitle() = " + track.getTitle());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

package org.kodejava.example.commons.beanutils;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Recording {
    private Long id;
    private String title;
    private List tracks = new ArrayList<>();
    private Map mapTracks = new HashMap<>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public List getTracks() {
        return tracks;
    }

    public void setTracks(List tracks) {
        this.tracks = tracks;
    }

    public void setMapTracks(Map mapTracks) {
        this.mapTracks = mapTracks;
    }

    public Map getMapTracks() {
        return mapTracks;
    }
}

And here is the result of our program.

track.getTitle() = I Saw Her Standing There