How to display different list commands in JShell in Java 9?

JShellIntroduced in Java 9, it is a command line tool that allows us to enter simple statements, expressions, methods and classes without main() methods.

When we can enter the code in JShell, the code has been assigned a unique ID. The ID starts at 1 and increments with each command entered in JShell. The same is true for libraries loaded on startup. For each import, a unique ID is assigned. It starts with $1 and increments with each code loaded ($2, $3, etc.). There is an internal command to list all code loaded and entered during a session, then use the "/list" command.

<strong>/list
/list [ID]
/list [Code_Name]
/list -start
/list -all</strong>

• /list: This command displays all active code entered in the current session (excluding code loaded when JShell is started).
• /list [ID]: This command displays the source code corresponding to the entered ID.
• /list [Code_Name]: Displays the source code corresponding to the entered name.
• /list -start: This command displays all code loaded when JShell starts. When you start a session, all imports that are preloaded by default will be displayed, and may also display your own code that you want to preload (this is explained in the Custom JShell startup chapter in Part 3).
• /list -all: This command lists all active, inactive, error, and preload code entered during a JShell session.

In the following code snippet, we can use the "/list -all" command to list all input imports, expressions, etc.

<strong>jshell> /imports
|    import java.io.*
|    import java.math.*
|    import java.net.*
|    import java.nio.file.*
|    import java.util.*
|    import java.util.concurrent.*
|    import java.util.function.*
|    import java.util.prefs.*
|    import java.util.regex.*
|    import java.util.stream.*
jshell> LocalDate localDate = LocalDate.of(2020, 04, 10)
|   Error:
|   cannot find symbol
|     symbol: class LocalDate
|   LocalDate localDate = LocalDate.of(2020, 04, 10);
|   ^-------^
|   Error:
|   cannot find symbol
|     symbol: variable LocalDate
|   LocalDate localDate = LocalDate.of(2020, 04, 10);
|   ^-------^

jshell> int x = 10
x ==> 10

jshell> public enum Operate {
...>       ADDITION,
...>       DIVISION;
...>    }
| created enum Operate

jshell> /list -all

s1 : import java.io.*;
s2 : import java.math.*;
s3 : import java.net.*;
s4 : import java.nio.file.*;
s5 : import java.util.*;
s6 : import java.util.concurrent.*;
s7 : import java.util.function.*;
s8 : import java.util.prefs.*;
s9 : import java.util.regex.*;
s10 : import java.util.stream.*;
e1 : LocalDate localDate = LocalDate.of(2020, 04, 10);
1 : int x = 10;
2 : public enum Operate {
       ADDITION,
       DIVISION;
    }</strong>

In the code snippet below, we can name a variable, a method, or even a type with the same name. We can then use the "/list" command to display the different occurrences of the name and the corresponding types.

<strong>jshell> int x = 10
x ==> 10

jshell> public int x(int y) {
...>       return y;
...>    }
| created method x(int)

jshell> public long x(long y, long z) {
...>       return y + z;
...>    }
| created method x(long,long)

jshell> /list x

1 : int x = 10;
2 : public int x(int y) {
       return y;
    }
3 : public long x(long y, long z) {
       return y + z;
    }</strong>

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