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Questions and Answers
Which of the following best describes the syntax for constructing a string in Java?
Which of the following best describes the syntax for constructing a string in Java?
What is the result of the following code: String s = 'Java'; s = 'HTML';
What is the result of the following code: String s = 'Java'; s = 'HTML';
What does it mean for a String object to be immutable?
What does it mean for a String object to be immutable?
Why does the Java Virtual Machine (JVM) use a unique instance for string literals with the same character sequence?
Why does the Java Virtual Machine (JVM) use a unique instance for string literals with the same character sequence?
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What is the purpose of using interned strings in Java?
What is the purpose of using interned strings in Java?
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What happens when the code 'String s1 = "Welcome to Java";' is executed?
What happens when the code 'String s1 = "Welcome to Java";' is executed?
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What will the output be for the code 'System.out.println("s1 == s2 is " + (s1 == s2));'?
What will the output be for the code 'System.out.println("s1 == s2 is " + (s1 == s2));'?
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What is the result of comparing two strings with the 'compareTo' method if they are equal?
What is the result of comparing two strings with the 'compareTo' method if they are equal?
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What does the 'regionMatches' method do in Java?
What does the 'regionMatches' method do in Java?
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What does the 'startsWith' method do in Java?
What does the 'startsWith' method do in Java?
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Study Notes
Constructing a String in Java
- In Java, a string is constructed using double quotes, for example:
String s = "Java";
String Immutability
- A String object is immutable, meaning its value cannot be changed after it is created
- When a new value is assigned to a String variable, a new String object is created, and the original object remains unchanged
String Literals and JVM
- The Java Virtual Machine (JVM) uses a unique instance for string literals with the same character sequence to conserve memory
- This means that if multiple strings have the same character sequence, they will reference the same object in memory
Interned Strings
- Interned strings are strings that are stored in a pool, allowing for efficient reuse of identical strings
- The purpose of interned strings is to reduce memory usage by avoiding the creation of duplicate strings
String Creation and Interning
- When executing the code
String s1 = "Welcome to Java";, a new string object is created and interned in the string pool - If a string with the same character sequence already exists in the pool, the existing object is reused
Comparing Strings
- Comparing two strings with the
compareTomethod returns 0 if they are equal - The
compareTomethod compares the lexicographical order of the strings
String Methods
- The
regionMatchesmethod checks if a region of one string matches a region of another string - The
startsWithmethod checks if a string starts with a specified prefix
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Description
Test your knowledge of constructing strings and their immutability in Java. This quiz covers the syntax for creating strings and the concept of immutability, using examples and explanations from EIE3320 Chapter 9 at The Hong Kong Polytechnic University.
