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chmod +x src/java-shebang-example
./src/java-shebang-example

javac --source 12 --enable-preview src/SwitchPreview.java

java --source 12 --enable-preview src/SwitchPreview.java

java src/TeeingCollectorProblem.java 

Stream.of('5', 't', 'o', '9', 'p', '1', 'h')
        .collect(Collectors.teeing(
                Collectors.filtering(Character::isLetter, Collectors.toList()),
                Collectors.filtering(not(Character::isLetter), Collectors.toList()),
                List::of
        ));

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-12.jdk/Contents/Home

java --source 12 --enable-preview src/RawStringLiteralsPreview.java

if (obj instanceof String str) {
    str.trim();
} else {
    // can't use str here
}

@Override 
public boolean equals(Object o) { 
    return (o instanceof CaseInsensitiveString cis)
        && cis.equalsIgnoreCase(s); 
}

String formatted =
    switch (obj) {
        case Integer i -> String.format("int %d", i); 
        case Byte b    -> String.format("byte %d", b); 
        case Long l    -> String.format("long %d", l); 
        case Double d  -> String.format("double %f", d); 
        case String s  -> String.format("String %s, s);
        default        -> String.format("Object %s", obj);
    };

BiFunction<Integer, String, String> biss = (i, _) -> String.valueOf(i);

Map<String, Integer> msi = new HashMap<>();

String key = computeSomeKey();
msi.computeIfAbsent(key, key -> key.length()) //error

class Foo {
   static boolean g(String s) { return false }
   static boolean g(Integer i) { return false }
}

m(Foo::g) //ambiguous

source code: a.to_b.to_c.to_d.num = 99 // a is null
  thrown msg: 'a' is null. Can not read field 'to_b'

source code: nullInstanceField.testNullMessages()
  thrown msg: 'this.nullInstanceField' is null. Can not invoke method 'NullPointerExceptionTest.testNullMessages()V'.
  
source code: a.getB().getBfromB().getC().getD().num = 99 // a.getB().getBfromB().getC().getD() is null
  thrown msg: The return value of 'NullPointerExceptionTest$C.getD()LNullPointerExceptionTest$D;' is null. Can not write field 'num'.