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| | Use the following code: | | | Use the following code: |
| <source lang="java"> | | <source lang="java"> |
− | package j12.preview;
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− |
| |
| public class Test { | | public class Test { |
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| <source lang="java"> | | <source lang="java"> |
− | package j12.preview;
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− |
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| public class Test { | | public class Test { |
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| <source lang="java"> | | <source lang="java"> |
− | package j12.preview;
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− |
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| public class Test { | | public class Test { |
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| <source lang="java"> | | <source lang="java"> |
− | package j12.preview;
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− |
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| public class Test { | | public class Test { |
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Revision as of 05:35, 19 March 2019
= NOTE: THE PAGE IS UNDER CONSTRUCTION
This is an informal page listing examples of features that are implemented by the Java 12 Support. You are welcome to try out these examples. If you find bugs, please file a bug after checking for a duplicate entry here
|
Feature / Steps
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Expected Result
|
The Pre-requisite: Java 12 JRE Support
|
Add Java 12 JRE
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Use Window -> Preferences-> Java -> Installed JREs -> Add...
[note: Eclipse -> Preferences in Mac / Window -> Preferences in Windows]
|
Java 12 JRE recognized as a valid JRE
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Project JRE
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In Package Explorer Use project's context menu and add Java 12 JRE |
JRE specific (eg Object) gets resolved in the project.
|
Package Explorer
|
Go to Package Explorer and expand the Java 12 JRE |
Modules (eg java.base etc) are listed in the package explorer view
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The First Step: Java 12 Compliance
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Set Project Compliance in Package Explorer
|
Context Menu of Project -> Properties -> Set project-specific, drop down to 12
|
12 is shown in the drop down list.
A checkbox to enable preview features is available on the preference page.
|
Basic Necessity : Compilation and Error Reporting
|
Positive Compilation 1 (Switch Statement with multi-label case with colon)
|
Use the following code:
public class X {
public void foo(int i) {
switch (i) {
case 0, 1, 2: System.out.println("Hello");
default : System.out.println("World");
}
}
public static void main(String[] argv) {
new X().foo(2);
}
}
|
-
|
Positive Compilation 2 (Switch Statement with case with arrow)
|
Use the following code:
public class X {
@SuppressWarnings("preview")
public void foo(int i) {
switch (i) {
case 2 -> System.out.println("Hello");
default -> System.out.println("World");
}
}
public static void main(String[] argv) {
new X().foo(2);
}
}
|
Code compiles (with a preview warning) and while running prints only "Hello" (because a break is implicit after every case with an arrow.
|
Positive Compilation
|
Use the following code:
public class Test {
enum Day {
MON, TUE, WED, THUR, FRI, SAT, SUN
};
@SuppressWarnings("preview")
public String getDay_1 (Day today) {
String day = switch(today) {
case MON, TUE, WED, THUR, FRI -> "Weekday";
case SAT, SUN -> "Weekend";
};
return day;
}
}
|
Code compiles
|
Compiler error Case
|
public class Test {
enum Day {
MON, TUE, WED, THUR, FRI, SAT, SUN
};
public String getDay_1 (Day today) {
String day = switch(today) {
case MON, TUE, WED, THUR, FRI: break "Weekday";
case SAT, SUN: break "Weekend";
};
return day;
}
}
|
Compiler error is shown for preview feature.
Quick fix is available to enable the preview feature in the preferences.
|
Compiler Warning Case
|
public class Test {
enum Day {
MON, TUE, WED, THUR, FRI, SAT, SUN
};
public String getDay_1 (Day today) {
String day = switch(today) {
case MON, TUE, WED, THUR, FRI: break "Weekday";
case SAT, SUN: break "Weekend";
};
return day;
}
}
|
Compiler warning is shown for preview feature
|
Compiler Error Case
|
public class Test {
enum Day {
MON, TUE, WED, THUR, FRI, SAT, SUN
};
@SuppressWarnings("preview")
public String getDay_1 (Day today) {
String day = switch(today) {
case MON : break "Weekday";
case SAT, SUN : break "Weekend";
};
return day;
}
}
|
Compiler error is shown
|