Migrate to Java 17

Let's migrate to Java 17 so as not to fall too far behind
the latest LTS version (currently, 21).

Contributoring authors:
@baskargopinath, @bennyLCK, @billyhoce, @gongg21, @hjungwoo01,
@jedkohjk, @jyue487, @itstrueitstrueitsrealitsreal, @brein62,
@aureliony, @ljy0422, @macareonie, @ryanozx, @Carlintyj,
@teoks0199, @drustanyjt

.github/workflows/gradle.yml

@@ -29,10 +29,10 @@ jobs:
       - name: Validate Gradle Wrapper
         uses: gradle/wrapper-validation-action@v1
 
-      - name: Setup JDK 11
+      - name: Setup JDK 17
         uses: actions/setup-java@v1
         with:
-          java-version: '11'
+          java-version: '17'
           java-package: jdk+fx
 
       - name: Build and check with Gradle

build.gradle

@@ -8,8 +8,8 @@ plugins {
 
 mainClassName = 'seedu.address.Main'
 
-sourceCompatibility = JavaVersion.VERSION_11
-targetCompatibility = JavaVersion.VERSION_11
+sourceCompatibility = JavaVersion.VERSION_17
+targetCompatibility = JavaVersion.VERSION_17
 
 repositories {
     mavenCentral()

docs/DeveloperGuide.md

@@ -317,7 +317,7 @@ Priorities: High (must have) - `* * *`, Medium (nice to have) - `* *`, Low (unli
 
 ### Non-Functional Requirements
 
-1.  Should work on any _mainstream OS_ as long as it has Java `11` or above installed.
+1.  Should work on any _mainstream OS_ as long as it has Java `17` or above installed.
 2.  Should be able to hold up to 1000 persons without a noticeable sluggishness in performance for typical usage.
 3.  A user with above average typing speed for regular English text (i.e. not code, not system admin commands) should be able to accomplish most of the tasks faster using commands than using the mouse.
 

docs/SettingUp.md

@@ -19,7 +19,7 @@ Follow the steps in the following guide precisely. Things will not work out if y
 First, **fork** this repo, and **clone** the fork into your computer.
 
 If you plan to use Intellij IDEA (highly recommended):
-1. **Configure the JDK**: Follow the guide [_[se-edu/guides] IDEA: Configuring the JDK_](https://se-education.org/guides/tutorials/intellijJdk.html) to to ensure Intellij is configured to use **JDK 11**.
+1. **Configure the JDK**: Follow the guide [_[se-edu/guides] IDEA: Configuring the JDK_](https://se-education.org/guides/tutorials/intellijJdk.html) to ensure Intellij is configured to use **JDK 17**.
 1. **Import the project as a Gradle project**: Follow the guide [_[se-edu/guides] IDEA: Importing a Gradle project_](https://se-education.org/guides/tutorials/intellijImportGradleProject.html) to import the project into IDEA.<br>
   :exclamation: Note: Importing a Gradle project is slightly different from importing a normal Java project.
 1. **Verify the setup**:

docs/UserGuide.md

@@ -12,7 +12,7 @@ AddressBook Level 3 (AB3) is a **desktop app for managing contacts, optimized fo
 
 ## Quick start
 
-1. Ensure you have Java `11` or above installed in your Computer.
+1. Ensure you have Java `17` or above installed in your Computer.
 
 1. Download the latest `addressbook.jar` from [here](https://github.com/se-edu/addressbook-level3/releases).