# StructuredTaskScope (JEP 505 in 25). Fifth preview in 25, sixth in 26, seventh in 27. $ javac StructuredHub.java (JDK 25, no flag) /lanes/src/StructuredHub.java:1: error: StructuredTaskScope is a preview API and is disabled by default. import java.util.concurrent.StructuredTaskScope; ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:15: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open()) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: Joiner is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) 5 errors exit=1 $ javac --enable-preview --release 25 StructuredHub.java (JDK 25) exit=0 $ java --enable-preview StructuredHub (JDK 25) java.version = 25.0.4.1 CHECK ok : fan-out: both results joined: Dashboard[user=user-7, order=order-for-7] CHECK ok : anySuccessfulResultOrThrow(): the first result wins and the slow subtask is cancelled $ javac StructuredHub.java (JDK 26, no flag) /lanes/src/StructuredHub.java:1: error: StructuredTaskScope is a preview API and is disabled by default. import java.util.concurrent.StructuredTaskScope; ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:15: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open()) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: Joiner is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: cannot find symbol try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ symbol: method anySuccessfulResultOrThrow() location: interface Joiner /lanes/src/StructuredHub.java:24: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) 6 errors exit=1 $ javac --enable-preview --release 26 StructuredHub.java (JDK 26) /lanes/src/StructuredHub.java:24: error: cannot find symbol try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ symbol: method anySuccessfulResultOrThrow() location: interface Joiner 1 error exit=1 $ javac StructuredHub.java (JDK 27, no flag) /lanes/src/StructuredHub.java:1: error: StructuredTaskScope is a preview API and is disabled by default. import java.util.concurrent.StructuredTaskScope; ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:15: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open()) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: Joiner is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) /lanes/src/StructuredHub.java:24: error: cannot find symbol try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ symbol: method anySuccessfulResultOrThrow() location: interface Joiner /lanes/src/StructuredHub.java:24: error: StructuredTaskScope is a preview API and is disabled by default. try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ (use --enable-preview to enable preview APIs) 6 errors exit=1 $ javac --enable-preview --release 27 StructuredHub.java (JDK 27) /lanes/src/StructuredHub.java:24: error: cannot find symbol try (var scope = StructuredTaskScope.open(StructuredTaskScope.Joiner.anySuccessfulResultOrThrow())) { ^ symbol: method anySuccessfulResultOrThrow() location: interface Joiner 1 error exit=1 $ javac --enable-preview --release 26 StructuredHubNew.java (JDK 26) exit=0 $ java --enable-preview StructuredHubNew (JDK 26) java.version = 26.0.2.1 CHECK ok : anySuccessfulOrThrow(): the first result wins $ javac --enable-preview --release 27 StructuredHubNew.java (JDK 27) exit=0 $ java --enable-preview StructuredHubNew (JDK 27) java.version = 27 CHECK ok : anySuccessfulOrThrow(): the first result wins