String Equality and Case Conversion

Which method checks two Java strings for content equality rather than reference equality?

• compare() compares generic objects

• compareTo() orders lexicographically

• equals() compares string contents

• == operator compares object references

Given: String s1 = "Hello"; String s2 = s1.toUpperCase(); What is printed by System.out.println(s1 == s2)?

• true because both have same letters

• false because toUpperCase creates new object

• true because String literals are interned

• false because equals compares references

What does str.equalsIgnoreCase("test") evaluate when str holds any casing of "TeSt"?

• Checks whether strings are interned

• Compares strings including case sensitivity

• Converts str to lowercase permanently

• Compares strings ignoring case differences

Given: String s1 = "abc"; String s2 = "ABC"; System.out.println(s1.equalsIgnoreCase(s2)); What is printed?

• true

• false

Given: String s = "Java"; System.out.println(s.toLowerCase().equals("java")); What is the output?

• false

• true

Given: String s = "abc"; System.out.println(s.compareTo("abd")); Which best describes the printed value?

• A compilation error

• The exact value zero

• A negative number

• A positive number

Given: String s1 = "Hello"; String s2 = s1; What does System.out.println(s1 == s2) print?

• true

• false

• null

• throws error

Given: String s = "abc"; What does System.out.println(s == s.intern()) print, and why is that typical?

• false, literals are always heap only

• true, intern compares content only

• false, intern creates a new object

• true, both refer to pooled literal

Given: String s = "abc"; What is the result of System.out.println(s.equals("ABC".toLowerCase())) and the reason?

• false, case conversion fails at runtime

• true, intern makes both same object

• false, equals checks references only

• true, lowercase equals same content

What is the difference between == and equals() for Strings?

• == compares references; equals() compares content

• No difference

• == compares content; equals() compares references

• Both compare references