למחלקת System ב-Java יש שתי שיטות המשמשות לקריאת מאפייני מערכת:
- פלט: לחץ כָּאן כדי לראות את הפלט
תיאור השיטות:
זה מבוסס על צמד מפתח - ערך כפי שהוזכר בטבלה המופיעה להלן.
תחביר:
public static String getProperty(String key) Parameters : key : key whose system property we want Returns : System property as specified the key Null : if there is no property present with that key.
// Java Program illustrating the working of getProperty(String key) method import java.lang.*; import java.util.Properties; public class NewClass { public static void main(String[] args) { // Printing Name of the system property System.out.println('user.dir: '+System.getProperty('user.dir')); // Fetches the property set with 'home' key System.out.println('home: '+System.getProperty('home')); // Resulting in Null as no property is present // Printing 'name of Operating System' System.out.println('os.name: '+System.getProperty('os.name')); // Printing 'JAVA Runtime version' System.out.println('version: '+System.getProperty('java.runtime.version' )); // Printing 'name' property System.out.println('name: '+System.getProperty('name' )); // Resulting in Null as no property is present } }
user.dir: /tmp/hsperfdata_bot home: null os.name: Linux version: 1.8.0_101-b13 name: null
תחביר:
public static String getProperty(String key String def) Parameters : key : system property def : default value of the key to be specified Returns : System Property Null : if there is no property present with that key.
// Java Program illustrating the working of // getProperty(String key String definition) method import java.lang.*; import java.util.Properties; public class NewClass { public static void main(String[] args) { // use of getProperty(String key String definition) method // Here key = 'Hello' and System Property = 'Geeks' System.out.println('Hello property : ' + System.getProperty('Hello' 'Geeks')); // Here key = 'Geek' and System Property = 'For Geeks' System.out.println('System-property :' + System.getProperty('System' 'For Geeks')); // Here key = 'Property' and System Property = null System.out.println('Property-property :' + System.getProperty('Property')); } }
Hello key property : Geeks System key property :For Geeks Property key property :null
אפשר גם לשנות את הסט הקיים של מאפייני המערכת באמצעות שיטת System.setProperties() . יש מספר של צמד מפתח-ערך בקובץ המאפיינים חלקם הם כדלקמן:
Keys Values --> os.version : OS Version --> os.name : OS Name --> os.arch : OS Architecture --> java.compiler : Name of the compiler you are using --> java.ext.dirs : Extension directory path --> java.library.path : Paths to search libraries whenever loading --> path.separator : Path separator --> file.separator : File separator --> user.dir : Current working directory of User --> user.name : Account name of User --> java.vm.version : JVM implementation version --> java.vm.name : JVM implementation name --> java.home : Java installation directory --> java.runtime.version : JVM version
public static Properties getProperties() Parameters : ------ Returns : System properties that JVM gets on your System gets from OS
// Java Program illustrating the working of getProperties() method import java.lang.*; import java.util.Properties; public class NewClass { public static void main(String[] args) { /* Use of getProperties() method System class refers to the JVM on which you are compiling your JAVA code getProperty fetches the actual properties that JVM on your System gets from your Operating System */ System.out.println('Following are the JVM information of your OS :'); System.out.println(''); // Property Object Properties jvm = System.getProperties(); jvm.list(System.out); } }
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