Add java17-features module: runnable demos and captured output for the ankurm.com java17-features article

2026-10-20 17:13:58 +00:00
parent 8b9447a393
commit 5a076c826f
23 changed files with 261 additions and 0 deletions
@@ -0,0 +1,6 @@
+$ javac src/RecordsDemo.java && java RecordsDemo     (17.0.20.1)
+toString        : Point[x=3, y=4]
+equals          : true   hashCode equal: true
+accessor        : p.x() = 3, distance = 5.0
+compact ctor    : negative coordinate: -1,2
+shallow         : Team[name=core, members=[a, b]]   <- the record's list changed after construction
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+$ javac src/SealedDemo.java && java SealedDemo     (17.0.20.1)
+Circle[r=1.0]              area = 3.142
+Square[side=2.0]           area = 4.000
+Rect[w=2.0, h=3.0]         area = 6.000
+permitted       : [Circle, Square, Rect]
+isSealed        : true
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+$ javac src/TextBlocksDemo.java && java TextBlocksDemo     (17.0.20.1)
+{
+  "name": "Ankur",
+  "city": "Mumbai"
+}
+lines           : 4
+backslash-newline: joined on one line
+formatted       : Hello, reader!
@@ -0,0 +1,5 @@
+$ javac src/SwitchExprDemo.java && java SwitchExprDemo     (17.0.20.1)
+MON -> 9 working hours
+SAT -> 0 working hours
+WED -> 8 working hours
+old fall-through: one two
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+$ javac src/PatternInstanceofDemo.java && java PatternInstanceofDemo     (17.0.20.1)
+long string hello
+other hi
+int 42
+Stream.toList   : [1, 2, 3]
+toList() result is unmodifiable
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+$ javac src/HelpfulNpeDemo.java && java HelpfulNpeDemo     (17.0.20.1)
+Cannot read field "city" because "u.address" is null
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+$ javac src/EncapsulationDemo.java && java EncapsulationDemo     (11.0.32.1)
+WARNING: An illegal reflective access operation has occurred
+WARNING: Illegal reflective access by EncapsulationDemo (file:/…/) to field java.lang.String.value
+WARNING: Please consider reporting this to the maintainers of EncapsulationDemo
+WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
+WARNING: All illegal access operations will be denied in a future release
+read String.value: byte[]
+
+$ javac src/EncapsulationDemo.java && java EncapsulationDemo     (17.0.20.1)
+java.lang.reflect.InaccessibleObjectException: Unable to make field private final byte[] java.lang.String.value accessible: module java.base does not "opens java.lang" to unnamed module @<hash>
+
+$ java --add-opens java.base/java.lang=ALL-UNNAMED EncapsulationDemo     (17.0.20.1)
+read String.value: byte[]
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+$ javac src/RandomDemo.java && java RandomDemo     (17.0.20.1)
+L64X128MixRandom nextInt(100) x3: 98 1 80
+ThreadLocalRandom implements RandomGenerator: true
+algorithms >= 10: true
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+$ javac broken/SealedViolation.java     (17.0.20.1)
+broken/SealedViolation.java:5: error: class is not allowed to extend sealed class: Shape (as it is not listed in its permits clause)
+    record Triangle(double b, double h) implements Shape {}
+    ^
+1 error
+
+$ javac broken/RecordFieldMutation.java     (17.0.20.1)
+broken/RecordFieldMutation.java:3: error: cannot assign a value to final variable x
+    record Point(int x, int y) { void move() { this.x = 10; } }
+                                                   ^
+1 error
+
+$ javac broken/SwitchPatternOn17.java     (17.0.20.1)
+broken/SwitchPatternOn17.java:3: error: patterns in switch statements are a preview feature and are disabled by default.
+    static String f(Object o) { return switch (o) { case String s -> "string"; default -> "other"; }; }
+                                                         ^
+  (use --enable-preview to enable patterns in switch statements)
+1 error