Overall, I think last week two tests are very difficult, do the test also took a long time, I think because the knowledge of the book a lot, I have not understood well, so still want to read more well, a lot of books on the knowledge points omitted or read once forgotten.
A. No other class can declare an object with an inner class of a class.
B. The name format of the internal class bytecode file is "outer nested class name $ internal
The class name.
C. The class body of an inner class can declare class variables and class methods.
D. The inner class is in the member position, so it can be decorated by private.
Answer: ABD (C-item error is not allowed in the class body of the inner class to declare class variables and class methods.) ）
A. True
B. False
Answer: B (for serious errors, described by the error class, and for non-serious problems, it is described by the exception class.) ）
A. Once the try section throws an exception object, the try section immediately ends execution and turns to the corresponding catch section.
B. A catch code block defines code that is bound to execute, which is typically used to close a resource.
C. The Try-catch statement can consist of several catch, dealing with the exception that occurs.
D. Exceptions listed in the catch brackets must not have an inheritance relationship, or a compilation error will occur.
Answer: ACD (item B: The finally code block defines code that is bound to execute, which is typically used to close a resource.) For the exception of the part, if not done finally, then the program is flawed, each call to the resources and then release the resources is necessary, otherwise the operating pressure will be particularly large. )
A. True
B. False
Answer: B (the file class does not involve read and write operations on files.) ）
A. File (file parent, String child)
B. File (String pathname)
C. File (string parent, String child)
D. File (URI Uri)
Answer: ABCD
A.public long length(): Get file length
B.public int hashCode(): Calculates the hash code for this file
C.public String toString(): Returns the path name string for this abstract pathname
D.public Boolean isFile(): Determines whether a file is a normal file, not a directory
Answer: B (public int hashCode(): Computes the hash code for this abstract pathname.) ）
A. True
B. False
Answer: B (InputStream is the parent class)
A. You can use the FileOutputStream class to write to a file.
B. The FileOutputStream class is constructed by FileOutputStream (file file), FileOutputStream (String name), FileOutputStream (file file, Boolean append) and so on.
C. For the FileOutputStream (String name) method, the file specified by the parameter name is called the source of the output stream.
D. If the output stream points to a file that already exists, the output stream refreshes the file so that the length of the file is 0.
Answer: ABD (the file specified in the parameter name in C is called the destination of the output stream. )
A. You can read a line of text by calling the ReadLine () method of the BufferedReader object.
B. BufferedReader has a method for writing a return line character to a file: NewLine ().
C. When the BufferedWriter stream calls flush () to flush the cache or when the close () method is called off, the cached content is written to the destination even if the cache does not overflow.
D. You can connect the BufferedWriter stream with the FileWriter stream, and then use the BufferedWriter stream to write the data to the destination.
Answer: B
A. Using scanner and regular expressions to parse a file is characterized by a space exchange for time.
B. When parsing a word that is not a numeric word, calling the Nextint () or nextdouble () method will occur inputmismatchexception exception.
C. Create a scanner object that points to the file you want to parse, and you can use the Usedelimiter method to specify a regular expression as a split mark.
D. Regular expression \b (?! ABC) \w) +\b can be used to match words that do not contain ABC.
Answer: BCD (a uses scanner and regular expressions to parse a file is characterized by time for space)
A. An exception may have occurred creating the file object.
B. The Bufferedread stream can point to the FileInputStream stream.
C. The Bufferedwrite stream can point to the FileWrite stream.
D. Once the Randomaccessfile stream points to the file, it refreshes the file.
Answer: C
A. Duplicate elements are not allowed, elements have no order
B. Duplicate elements are not allowed, elements are in order
C. Allow repeating elements, elements in order
D. Allow repeating elements, elements without order
Answer: C
A. Public E GetLast () returns the last element of this list. If this list is empty, Nosuchelementexception is thrown.
B. public void AddFirst (e e) Inserts the specified element at the beginning of this list. E is the element to be added.
C. The public boolean add (e E) is equivalent to AddLast (e).
D. public boolean remove (Object O) Overrides class Abstractcollection
Answer: ABCD (through the query API)
A. public boolean IsEmpty () returns True if this mapping does not contain a key-value mapping relationship.
B. Public V get (Object key) returns the value mapped by the specified key, or throws an exception if the mapping does not contain a mapping relationship for the key.
C. Public V put (K key, V value) associates the specified value with the specified key in this mapping. If the map previously contained a mapping of the key, the values defined first prevail.
D. Public Object Clone () returns a shallow copy of this HASHMAP instance: The key and the value itself are not copied.
Answer: AD (via the query API: B: If this map does not contain a mapping relationship for the key, NULL is returned.) C: If the map previously contained a mapping of the key, the old value is replaced)
E I The public boolean add (e E) Adds the specified element to this set. If this set already contains such an element, the call does not change this set and returns FALSE.
C. public boolean addall (collection<? extends e> c) adds all the elements in the specified Collection to this set. Returns True if this set is changed because of a call.
D. Public e Lower (e e) returns the largest element in this set that is strictly less than the given element, or null if no such element exists.
Answer: BCD (Item A: ClassCastException exception is thrown if the specified object cannot be compared to the current element in the set. ）
A. "John" = "John"
E I "John". Equals ("John")
C. "John" = "John"
D. "John". Equals (New String ("John"))
Answer: C
A. True
B. False
Answer: A
A. True
B. False
Answer: B
A. True
B. False
Answer: B
A. Compares two strings in a dictionary order. The comparison is based on the Unicode values of the individual characters in the string.
B. If this string object is in the dictionary order before the parameter string, the comparison result is a positive integer.
C. If they have different characters at one or more index positions, assuming that k is the minimum value for such an index, COMPARETO returns the difference between the two strings at position K at two char values, which is the value: This.charat (k)-anotherstring.charat (k)
D. If there are no different index positions for the characters, the dictionary order of shorter strings precedes the longer strings. In this case, COMPARETO returns the difference between the two string lengths
E. CompareTo returns 0 only if the method equals (Object) returns True.
Answer: ACDE (b returns a negative integer)
A. public string substring (int beginindex) returns a substring starting at the character at the specified index until the end of this string.
B. The public string substring (int beginindex, int endIndex) substring starts at the specified beginindex until the character at the index EndIndex.
C. "Emptiness". Substring (9) The return value is "".
D. "Smiles". Substring (1, 5) The return value is "mile".
E. If Beginindex is greater than endIndex, then substring (int beginindex, int endIndex) returns-1.
Answer: ACD (item B: The character at index EndIndex-1. E entry: Throws a Indexoutofboundsexception exception. ）
A. The data class in the Java.util package overrides the ToString () method.
B. Both arrays and point inherit the ToString method.
C. The place where the x.tostring () method is called can be replaced with "" +x.
D. Definition int[] Numbers = {1, 2, 3}; String S1 = "" +numbers;, then System.out.println (S1); The ToString method is called to output the array.
Answer: D (item D: If you want to print an array, the array must call the static method arrays.tostring, that is, string S1 = "" +numbers in the above program; change to string S1 = arrays.tostring (Numbers);. If you want to print a multidimensional array, you need to call the Arrays.deeptostring method. ）
A. The return value of getChars (int srcbegin, int srcend, char[] DST, int dstbegin) method is empty.
E I Srcend is the index of the last character in the string to copy.
C. A Indexoutofboundsexception exception is thrown when Srcbegin is greater than srcend.
D. The characters to be copied to the DST sub-array start at index Dstbegin and end at index Dstbegin + (srcend-srcbegin)-1
Answer: ACD (item B: Srcend is the index after the last character in the string to be copied. ）
A. \ba\w*\b matches a word that begins with the letter A
E I \d+ matches 1 or more consecutive digits.
C. \b\w{6}\b matches 6 or more characters.
D. [0-9] The meaning of the representation is exactly the same as the \d: a number
E. \s+ matches a string that does not contain whitespace characters.
F. (\d{1,3}.) {3}\d{1,3} is used to match an IP address.
Answer: Abde (c: \b\w{6}\b matches exactly 6 characters in a word. F: Each number in an IP address cannot be greater than 255, and the expression ignores this constraint. The Right thing is ((2[0-4]\d|25[0-5]|[ 01]?\d\d?).) {3} (2[0-4]\d|25[0-5]| [01]?\d\d?]. ）
A. You can use the static method of the system class public long
Currenttimemillis () Gets the current time of the system.
B. The public boolean equals (Object obj) method of the date class overrides equals in the class Object.
C. You can use the After () method if you compare the time and date of the two calendar. The After () return value is a Boolean type, which is equivalent to CompareTo (when) <0.
D. Use the static method of the Calendar class getinstance () to initialize a calendar object.
Test Center: C: It is equivalent to CompareTo (when) >0.
Answer: C
A. Before Java 8, the date was calculated using the DateFormat class.
B. It takes time for humans to understand, and it is recommended to use ToString () of the date class.
C. Now the international standard Time is GMT.
D. The new Date (System.currenttimemillis ()) is equivalent to the new date ()
Answer: D
A. public static double CBRT (double A) returns the cube root of a double value. If the argument is Nan, the result is Nan.
B. public static double cos (double A) returns the trigonometric cosine of the angle. If the argument is Nan or infinity, the result is Nan.
C. public static double floor (double a) returns the largest (closest to positive infinity) Double value, which is less than or equal to the parameter and equals an integer. If the argument is Nan or infinity, the result is Nan.
D. public static double log10 (double A) returns the logarithm of the base 10 of the double value. If the parameter is positive 0 or minus 0, then the result is negative infinity.
Answer: ABD (c: If the argument is NaN, infinity, positive 0, or minus 0, the result is the same as the parameter.) ）
A. int m =float.parsefloat ("567");
B. int m =short.parseshort ("567")
C. byte M =integer.parseint ("2");
D. float m =float.parsedouble ("2.9")
Answer: C
Which of the following statements is true for the following code? ( )
public class E {
public static void main (String args[]) {
String s1 = args[1];
String s2 = args[2];
String s3 = args[3];
System.out.println(s3);
}
}
A. A compilation error occurred on the program.
B. No compile error, execute program at command line: "Java E I love this game", program output this.
C. No compile error, execute program at command line: "Java E let us go", program no run exception.
D. No compile error, execute program at command line: "java E 0 1 2 3 4 5 6 7 8 9" program output 3.
Answer: D
Then according to the error hint, found that the time code problem, the class name of the case is wrong.
20165312 2017-2018-2 "Java Programming" 7th Week study Summary
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