DHTMLX Planning Engine Documentation

Subtree#

The scope of a scoped run. Set it as subtree in SolveOptions or PreviewOptions to reschedule one task's branch instead of the whole project. Create it with new Subtree(task) and chain withInclusive(false) to follow outgoing links only.

Declaration#

package org.dhtmlx.plen;

public class Subtree extends ValueRecord implements DeepCloneable<Subtree>

Constructors#

Subtree(Id)#

public Subtree(Id task)

Creates a scope rooted at task with inclusive = true. Subtree has no parameterless constructor.

Parameters

Name Type Description
task Id Root task ID, for example Id.str("a") or Id.num(1)

Fields#

Field Type Default Description
task Id set by the constructor Root task of the scope. The scope covers this task, its ancestors and descendants, and every task reached from them through outgoing links, transitively. Each task reached this way brings its own ancestors and descendants.
inclusive boolean true true also follows incoming links, so predecessors and their branches join the scope. false follows outgoing links only. The root is in scope either way.

Both fields are public and mutable.

Methods#

withTask#

public Subtree withTask(Id value)

Sets task and returns this instance for chaining.

withInclusive#

public Subtree withInclusive(boolean value)

Sets inclusive and returns this instance for chaining.

deepClone#

public Subtree deepClone()

Returns a new Subtree with the same task and inclusive. Implements DeepCloneable.

copy#

public Subtree copy()

Returns a shallow copy. Id is immutable, so the copy is independent of the original.

equals, hashCode, toString#

public boolean equals(Object other)
public int hashCode()
public String toString()

Value semantics, inherited from ValueRecord. Two scopes are equal when task and inclusive are equal, and hashCode follows the same fields. toString returns a readable form for logging, such as Subtree{task=a, inclusive=true}.

Errors#

If task is unknown or unscheduled, the call that receives the options throws InputException (unchecked) with kind = InputErrorKind.VALIDATION and path = "subtree.task".

Example#

Commit an edit to task a, then reschedule only a and the tasks linked downstream of it.

import java.util.List;
import org.dhtmlx.plen.*;

public class SubtreeExample {
  public static void main(String[] args) throws Exception {
    Moment monday = Moment.fromYmdHm(2026, 8, 10, 8, 0);
    ProjectData data = new ProjectData()
        .withTasks(List.of(
            new TaskData(Id.str("a")).withStartDate(monday).withDuration(2.0),
            new TaskData(Id.str("b")).withStartDate(monday).withDuration(1.0)))
        .withLinks(List.of(
            new LinkData().withId(Id.str("l1")).withSource(Id.str("a")).withTarget(Id.str("b"))));

    Project project = new Project();
    project.solve(data, new SolveOptions());

    SchedulingChanges changes = new SchedulingChanges();
    changes.tasks.update.add(new TaskUpdate(Id.str("a")).withDuration(Patch.of(3.0)));
    project.apply(changes);

    SolveOptions options = new SolveOptions()
        .withSubtree(new Subtree(Id.str("a")).withInclusive(false));
    ScheduleResult result = project.solve(null, options);
    for (Mutation update : result.updates) {
      System.out.println("task " + update.id + ": " + update.startDate + " .. " + update.endDate);
    }
    // task a: 2026-08-10 08:00 .. 2026-08-13 08:00
    // task b: 2026-08-13 08:00 .. 2026-08-14 08:00
  }
}