In Java, consider the following independent code fragments: A. StringBuffer sb1 = "abcd"; B. Boolean b = new Boolean("abcd"); C. byte b = 255; D. int x = 0x1234; E. float fl = 1.2; Which of the following statements about which fragments compile without error is correct?

Introduction / Context:
This Java question tests detailed knowledge of type compatibility, numeric ranges, and literal types in variable declarations. Some declarations may appear syntactically reasonable at first glance, but subtle rules about constructors, numeric limits, and default literal types cause several of them to fail compilation. Understanding which declarations are valid helps build stronger intuition about Java type rules.

Given Data / Assumptions:

• Each declaration A through E is considered independently.
• A: StringBuffer sb1 = "abcd";
• B: Boolean b = new Boolean("abcd");
• C: byte b = 255;
• D: int x = 0x1234;
• E: float fl = 1.2;
• We must identify which fragments compile without error.

Concept / Approach:
StringBuffer is a class, so assigning a string literal directly to a StringBuffer variable without using a constructor is not valid. The Boolean class has a constructor that accepts a String argument, so that declaration is valid. A byte in Java has a range of values from minus 128 to plus 127, so assigning 255 is out of range and causes a compile time error. Hexadecimal integers like 0x1234 are valid int literals. For floating point literals, values without suffix are treated as double by default; assigning a double literal directly to a float variable without a cast or suffix causes a compile time error.

Step-by-Step Solution:
Step 1: Examine fragment A. StringBuffer sb1 = "abcd"; attempts to assign a string literal to a StringBuffer reference without using new StringBuffer, so this does not compile. Step 2: Look at fragment B. Boolean b = new Boolean("abcd"); is legal because the Boolean constructor accepts a String argument, even though the value will be interpreted as false. Step 3: Consider fragment C. byte b = 255; exceeds the allowed range for byte, resulting in a compile time error. Step 4: Evaluate fragment D. int x = 0x1234; is a valid hexadecimal integer literal, so it compiles. Step 5: Review fragment E. float fl = 1.2; fails because 1.2 is a double literal by default and cannot be assigned to float without an explicit cast or the suffix f.

Verification / Alternative check:
If you write these declarations in a small Java file and compile it, you will see that only fragments B and D compile successfully. The compiler will complain about incompatible types in fragments A and E and about possible loss of precision in fragment C, confirming the theoretical analysis.

Why Other Options Are Wrong:
Option B claims that B, C, and D compile, but C does not compile because 255 is out of range for byte. Option C includes fragment A, which does not compile due to assigning a string literal directly to a StringBuffer. Option D says all fragments compile, which clearly contradicts the failures of A, C, and E. Option E suggests that only A and B compile, but A is invalid as explained.

Common Pitfalls:
Students often forget the numeric range of the byte type and assume that any small integer literal is acceptable. Another common issue is overlooking the default type of numeric literals; many learners do not realise that floating point literals are double by default in Java. It is also easy to confuse String and StringBuffer, assuming direct assignment is possible, which it is not without using a constructor or method such as append.

Final Answer:
The only declarations that compile successfully are those in fragments B and D, so the correct choice is only fragments B and D compile successfully..