单项选择题
A. The output is “Equal”
B. The output in “Not Equal”
C. An error at line 5 causes compilation to fall.
D. The program executes but does not print a message.
单项选择题 Whichstatementistruefortheclassjava.util.HashSet?()
单项选择题 Youneedtostoreelementsinacollectionthatguaranteesthatnoduplicatesarestoredandallelementscanbeaccessedinnaturalorder.Whichinterfaceprovidesthatcapability?()
填空题 3. string foo = “ABCDE”; 4. foo.substring(3); 5. foo.concat(“XYZ”); 6. Type the value of foo at line 6.()