UIAbility Launch Type

The launch type of the UIAbility component refers to the state of the UIAbility instance at startup. Three launch types are available:

• Singleton

• Multiton

• Specified

In this tutorial, we are focusing on Singleton and Multiton.

Singleton

singleton is the default launch type.

Each time startAbility() is called, if a UIAbility instance of this type already exists in the application process, the instance is reused. In other words, UIAbility of this type can have only one instance in the system, meaning that only one mission is displayed in the system application Recents.

Figure 1 Demonstration effect in singleton mode

To use the singleton mode, set launchType in the module.json5 file to singleton.

{
  "module": {
    ...
    "abilities": [
      {
        "launchType": "singleton",
        ...
      }
    ]
  }
}

Multiton

In multiton mode, each time startAbility() is called, a new UIAbility instance is created in the application process. Multiple missions are displayed for UIAbility of this type in Recents.

Figure 2 Demonstration effect in multiton mode

To use the multiton mode, set launchType in the module.json5 file to multiton.

{
  "module": {
    ...
    "abilities": [
      {
        "launchType": "multiton",
        ...
      }
    ]
  }
}

Specified

The specified mode is used in some special scenarios. For example, in a document application, you may want a document instance to be created each time you create a document, and you may also want to use the same document instance when you open an existing document.

Figure 3 Demonstration effect in specified mode

In the following example, there are two UIAbility components: EntryAbility and SpecifiedAbility (with the launch type specified).

You can learn more about Specified from this source.