To determine which lines will compile using Java 5 but not Java 1.4, let's analyze each line of code:
Line 4: long x1 = Long.valueOf("123");
This line will compile in both Java 5 and Java 1.4. The valueOf method returns a Long object, which can be assigned to a long variable.
Line 5: Long x2 = Long.valueOf("123");
This line will compile in both Java 5 and Java 1.4. Similar to line 4, the valueOf method returns a Long object, which can be assigned to a Long variable.
Line 6: long x3 = xL.longValue();
This line will compile in both Java 5 and Java 1.4. The longValue method returns a long value, which can be assigned to a long variable.
Line 7: Long x4 = xL.longValue();
This line will NOT compile in Java 1.4 but will compile in Java 5. In Java 1.4, the longValue method returns a long value, which cannot be directly assigned to a Long variable. In Java 5, it will automatically be boxed into a Long object.
Line 8: Long x5 = Long.parseLong("456");
This line will NOT compile in Java 1.4 but will compile in Java 5. In Java 1.4, the parseLong method returns a long value, which cannot be directly assigned to a Long variable. In Java 5, it will automatically be boxed into a Long object.
Line 9: long x6 = Long.parseLong("123");
This line will compile in both Java 5 and Java 1.4. The parseLong method returns a long value, which can be assigned to a long variable.
Based on the explanations above, the lines that will compile using Java 5 but will NOT compile using Java 1.4 are:
A. Line 4
D. Line 7
E. Line 8
Therefore, the correct answer is A, D, and E.