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]