JShell is a REPL (Read-Evaluate-Print-Loop) tool used to execute simple statements, evaluates it, and displays the result without a main() method. We can start it by simply type "jshell" in command-line prompt.
We need to get the system properties by using System.getProperty() and System.getProperties() methods.
In the below code snippet, we can able to display the system properties in the JShell tool by using static method property() of System class.
<strong>jshell> System.getProperty("java.class.path") </strong><strong>$1 ==> </strong><strong>"C:\Program Files\Java\jdk-9.0.4\lib;C:\json-jars\json.jar;.;C:\json-jars\json-simple.jar;.;C:\json-jars\gson.jar;.;C:\json-jars\commons-io.jar;.;C:\json-jars\jackson-core.jar;.;C:\json-jars\jackson-databind.jar;.;C:\json-jars\jackson-annotations.jar;.;C:\json jars\flexjson.jar;.;C:\json-jars\jackson-dataformat-xml.jar;.;C:\json-jars\stax2-api.jar;.;C:\json-jars\jackson-dataformat-csv.jar;.;C:\json-jars\javax.json.jar;.;C:\json jars\javax.json-api.jar;.;C:\json-jars\jackson-module-jsonSchema.jar;.;C:\json-jars\json-lib.jar;.;C:\json-jars\commons-lang.jar;.;C:\json-jars\commons-logging.jar;.;"</strong>
在下面的代码片段中,我们必须使用扩展了Hashtable的“properties”对象。因此,可以通过在JShell工具中使用“System.getProperties().forEach((k, v)”来列出所有属性作为键/值对.
<strong>jshell> System.getProperties().forEach((k, v) -> { System.out.printf("%s: %s\n", k, v); })</strong> <strong>sun.desktop: windows awt.toolkit: sun.awt.windows.WToolkit java.specification.version: 9 file.encoding.pkg: sun.io sun.cpu.isalist: amd64 sun.jnu.encoding: Cp1252 java.class.path: C:\Program Files\Java\jdk-9.0.4\lib;C:\json jars\json.jar;.;C:\json jars\json-simple.jar;.;C:\json jars\gson.jar;.;C:\json jars\commons-io.jar;.;C:\json jars\jackson-core.jar;.;C:\json jars\jackson-databind.jar;.;C:\json jars\jackson-annotations.jar;.;C:\json jars\flexjson.jar;.;C:\json jars\jackson-dataformat-xml.jar;.;C:\json jars\stax2-api.jar;.;C:\json jars\jackson-dataformat-csv.jar;.;C:\json jars\javax.json.jar;.;C:\json jars\javax.json-api.jar;.;C:\json jars\jackson-module-jsonSchema.jar;.;C:\json jars\json-lib.jar;.;C:\json jars\commons-lang.jar;.;C:\json jars\commons-logging.jar;.; java.vm.vendor: Oracle Corporation sun.arch.data.model: 64 user.variant: java.vendor.url: http://java.oracle.com/ user.timezone: os.name: Windows 8.1 java.vm.specification.version: 9 sun.java.launcher: SUN_STANDARD user.country: US sun.boot.library.path: C:\Program Files\Java\jdk-9.0.4\bin sun.java.command: jdk.jshell.execution.RemoteExecutionControl 54984 jdk.debug: release sun.cpu.endian: little user.home: C:\Users\User user.language: en java.specification.vendor: Oracle Corporation java.home: C:\Program Files\Java\jdk-9.0.4 file.separator: \ java.vm.compressedOopsMode: 32-bit line.separator: java.vm.specification.vendor: Oracle Corporation java.specification.name: Java Platform API Specification java.awt.graphicsenv: sun.awt.Win32GraphicsEnvironment user.script: sun.management.compiler: HotSpot 64-Bit Tiered Compilers java.runtime.version: 9.0.4+11 user.name: User path.separator: ; os.version: 6.3 java.runtime.name: Java(TM) SE Runtime Environment file.encoding: Cp1252 java.vm.name: Java HotSpot(TM) 64-Bit Server VM java.vendor.url.bug: http://bugreport.java.com/bugreport/ java.io.tmpdir: C:\Users\User\AppData\Local\Temp\ java.version: 9.0.4 user.dir: C:\Users\User\Desktop\Java 9 QNA os.arch: amd64 java.vm.specification.name: Java Virtual Machine Specification java.awt.printerjob: sun.awt.windows.WPrinterJob sun.os.patch.level: java.library.path: C:\Program Files\Java\jdk-9.0.4\bin;C:\Windows\Sun\Java\bin;C :\Windows\system32;C:\Windows;C:\Program Files\Java\jdk-9.0.4\bin;.;;. java.vm.info: mixed mode java.vendor: Oracle Corporation java.vm.version: 9.0.4+11 sun.io.unicode.encoding: UnicodeLittle java.class.version: 53.0</strong>
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