71. Which of the following is true about Java system properties?

1. 1. Java system properties are accessible by any process

   
   
   

   2. Java system properties are retrieved by System.getenv()

   
   
   

   3. Java system properties are set by System.setenv()

   
   
   

   4. Java system properties are accessible by processes they are added to

   
   
   

   5. None of these

   
   
   

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   Correct Option: D

   Java system properties are only used and accessible by the processes they are added.

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72. What does System.getProperty(“variable”) return?

1. 1. Null

   
   
   

   2. Runtime error

   
   
   

   3. Value stored in variable

   
   
   

   4. Compilation error

   
   
   

   5. None of these

   
   
   

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   Correct Option: A

   System.getProperty(“variable”) returns null value. Because, variable is not a property and if property does not exist, this method returns null value.

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73. Which system property stores installation directory of JRE?

1. 1. java.class.path

   
   
   

   2. java.home

   
   
   

   3. user.home

   
   
   

   4. user.dir

   
   
   

   5. None of these

   
   
   

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   Correct Option: B

   java.home is the installation directory of Java Runtime Environment.

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74. Java system properties can be set at runtime.

1. 1. Yes

   
   
   

   2. False

   
   
   

   3. True

   
   
   

   4. No

   
   
   

   5. A and C both

   
   
   

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   Correct Option: E

   Java system properties can be set at runtime using System.setProperty(name, value) or using System.getProperties().load() methods.

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75. What is true about the setProperties method?

1. 1. Changing the system properties within an application will affect future invocations

   
   
   

   2. setProperties method changes the set of Java Properties which are persistent

   
   
   

   3. setProperties writes the values directly into the file which stores all the properties

   
   
   

   4. setProperties method changes the set of Java Properties which are not persistent

   
   
   

   5. None of these

   
   
   

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   Correct Option: D

   The changes made by the setProperties method are not persistent. Hence, it does not affect future invocation.

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