Java练习题1(有答案).docx

第 1题 _ is an object-oriented programming language. 1、 Java 2、 C+ 3、 C 4、 Ada 5、 Pascal 答案 1 2 第 2题 _ is Architecture-Neutral. 1、 Java 2、 C+ 3、 C 4、 Ada 5、 Pascal 答案 1 第 3题 _ is a technical definition of the language that includes the syntax and semantics of the Java programming language. 1、 Java language specification 2、 Java API 3、 Java JDK 4、 Java IDE 答案 1 第 4题 _ consists of a set of separate programs for developing and testing Java programs, each of which is invoked from a command line. 1、 Java language specification 2、 Java API 3、 Java JDK 4、 Java IDE 答案 3 第 5题 _ provides an integrated development environment (IDE) for rapidly developing Java programs. Editing, compiling, building, debugging, and online help are integrated in one graphical user interface. 1、 Java language specification 2、 Java API 3、 Java JDK 4、 Java IDE 答案 4 第 6题 The main method header is written as: 1、 public static void main(string args) 2、 public static void Main(String args) 3、 public static void main(String args) 4、 public static main(String args) 5、 public void main(String args) 答案 3 第 7题 Which of the following statements is correct? 1、 Every line in a program must end with a semicolon. 2、 Every statement in a program must end with a semicolon. 3、 Every comment line must end with a semicolon; 4、 Every method must end with a semicolon; 5、 Every class must end with a semicolon; 答案 2 第 8题 Which of the following statements is correct to display Welcome to Java on the console? 1、 System.out.println( Welcome to Java ); 2、 System.out.println(Welcome to Java); 3、 System.println( Welcome to Java ); 4、 System.out.print( Welcome to Java ); 5、 System.out.print(Welcome to Java); 答案 2 5 第 9题 Which JDK command is correct to run a Java application in ByteCode.class? 1、 java ByteCode 2、 java ByteCode.class 3、 javac ByteCode.java 4、 javac ByteCode 5、 JAVAC ByteCode 答案 1 第 10题 Suppose you define a Java class as follows: public class Test In order to compile this program, the source code should be stored in a file named 1、 Test.class 2、 Test.doc 3、 Test.txt 4、 Test.java 5、 Any name with extension .java 答案 4 第 11题 The extension name of a Java bytecode file is 1、 .java 2、 .obj 3、 .class 4、 .exe 答案 3 第 12题 Which of the following lines is not a Java comment? 1、 /* comments */ 2、 / comments 3、 - comments 4、 /* comments */ 5、 * comments * 答案 3 5 第 13题 Which of the following are the reserved words? 1、 public 2、 static 3、 void 4、 class 答案 1 2 3 4 第 14题 To use JOptionPane in your program, you may import it using: 1、 import javax.swing.JOptionPane; 2、 import javax.swing.*; 3、 import javax.*; 4、 import javax.*.JOptionPane; 答案 1 2 第 15题 Which of the following are correct names for variables according to Java naming conventions? 1、 radius 2、 Radius 3、 RADIUS 4、 findArea 5、 FindArea 答案 1 4 第 16题 Which of the following are correct ways to declare variables? 1、 int length; int width; 2、 int length, width; 3、 int length; width; 4、 int length, int width; 答案 1 2 第 17题 _ is the Java assignment operator. 1、 = 2、 := 3、 = 4、 =: 答案 3 第 18题 Which of the following assignment statements is incorrect. 1、 i = j = k = 1; 2、 i = 1; j = 1; k = 1; 3、 i = 1 = j = 1 = k = 1; 4、 i = j = k = 1; 答案 3 4 第 19题 Which of the following is a constant, according to Java naming conventions? 1、 MAX_VALUE 2、 Test 3、 read 4、 ReadInt 5、 COUNT 答案 1 5 第 20题 To declare an int variable number with initial value 2, you write 1、 int number = 2L; 2、 int number = 2l; 3、 int number = 2; 4、 int number = 2.0; 答案 3 第 21题 Which of the following expressions will yield 0.5? 1、 1 / 2 2、 1.0 / 2 3、 (double) (1 / 2) 4、 (double) 1 / 2 5、 1 / 2.0 答案 2 4 5 第 22题 Which of the following expression results in a value 1? 1、 2 % 1 2、 15 % 4 3、 25 % 5 4、 37 % 6 答案 4 第 23题 -25 % 5 is _ 1、 1 2、 2 3、 3 4、 4 5、 0 答案 5 第 24题 -24 % -5 is _ 1、 3 2、 -3 3、 4 4、 -4 5、 0 答案 4 第 25题 To add number to sum, you write (Note: Java is case-sensitive) 1、 number += sum; 2、 number = sum + number; 3、 sum = Number + sum; 4、 sum += number; 5、 sum = sum + number; 答案 4 5 第 26题 Suppose x is 1. What is x after x -= 1? 1、 0 2、 1 3、 2 4、 -1 5、 -2 答案 1 第 27题 What is x after the following statements? int x = 1; int y = 2; x *= y + 1; 1、 x is 1; 2、 x is 2; 3、 x is 3; 4、 x is 4; 答案 3 第 28题 What is y displayed? public class Test public static void main(String args) int x = 1; int y = x + x+; System.out.println(y is + y); 1、 y is 1. 2、 y is 2. 3、 y is 3. 4、 y is 4. 答案 2 第 29题 What is y displayed in the following code? public class Test public static void main(String args) int x = 1; int y = x+ + x; System.out.println(y is + y); 1、 y is 1. 2、 y is 2. 3、 y is 3. 4、 y is 4. 答案 3 第 30题 What is the printout of the following code: double x = 5.5; int y = (int)x; System.out.println(x is + x + and y is + y); 1、 x is 5 and y is 6 2、 x is 6.0 and y is 6.0 3、 x is 6 and y is 6 4、 x is 5.5 and y is 5 5、 x is 5.5 and y is 5.0 答案 4 第 31题 Suppose x is a char variable with a value b . What is the printout of the statement System.out.println(+x)? 1、 a 2、 b 3、 c 4、 d 答案 3 第 32题 Suppose i is an int type variable. Which of the following statements display the character whose Unicode is stored in variable i? 1、 System.out.println(i); 2、 System.out.println(char)i); 3、 System.out.println(int)i); 4、 System.out.println(i + ); 答案 2 第 33题 The following code fragment reads in two numbers: Scanner input = new Scanner(System.in); int i = input.nextInt(); double d = input.nextDouble(); What are the correct ways to enter these two numbers? 1、 Enter an integer, a space, a double value, and then the Enter key. 2、 Enter an integer, two spaces, a double value, and then the Enter key. 3、 Enter an integer, an Enter key, a double value, and then the Enter key. 4、 Enter a numeric value with a decimal point, a space, an integer, and then the Enter key. 答案 1 2 3 第 34题 If you enter 1 2 3, when you run this program, what will be the output? import java.util.Scanner; public class Test1 public static void main(String args) Scanner input = new Scanner(System.in); System.out.print(Enter three numbers: ); double number1 = input.nextDouble(); double number2 = input.nextDouble(); double number3 = input.nextDouble(); / Compute average double average = (number1 + number2 + number3) / 3; / Display result System.out.println(average); 1、 1.0 2、 2.0 3、 3.0 4、 4.0 答案 2 第 35题 The expression (int)(76.0252175 * 100) / 100 evaluates to _. 1、 76.02 2、 76 3、 76.0252175 4、 76.03 答案 2 第 36题 According to Java naming convention, which of the following names can be variables? 1、 FindArea 2、 findArea 3、 totalLength 4、 TOTAL_LENGTH 5、 class 答案 2 3 第 37题 The _ method displays an input dialog for reading a string. 1、 String string = JOptionPane.showMessageDialog(null, Enter a string, Input Demo, JOptionPane.QUESTION_MESSAGE); 2、 String string = JOptionPane.showInputDialog(null, Enter a string, Input Demo, JOptionPane.QUESTION_MESSAGE); 3、 String string = JOptionPane.showInputDialog(Enter a string, Input Demo, JOptionPane.QUESTION_MESSAGE); 4、 String string = JOptionPane.showInputDialog(null, Enter a string); 5、 String string = JOptionPane.showInputDialog(Enter a string); 答案 2 4 5 第 38题 Analyze the following code. import javax.swing.*; public class ShowErrors public static void main(String args) int i; int j; String s = JOptionPane.showInputDialog(null, Enter an integer, Input, JOptionPane.QUESTION_MESSAGE); j = Integer.parseInt(s); i = (i + 4); 1、 The program cannot compile because j is not initialized. 2、 The program cannot compile because i does not have an initial value when it is used in i = i + 4; 3、 The program compiles but has a runtime error because i does not have an initial value when it is used in i = i + 4; 4、 The program compiles and runs fine. 答案 2 第 39题 Suppose x=10 and y=10. What is x after evaluating the expression (y 10) & (x- 10)? 1、 9 2、 10 3、 11 答案 2 第 40题 Suppose x=10 and y=10 what is x after evaluating the expression (y = 10) | (x+ 10). 1、 9 2、 10 3、 11 答案 2 第 41题 Suppose x = 1, y = -1, and z = 1. What is the printout of the following statement? (Please indent the statement correctly first.) if (x 0) if (y 0) System.out.println(x 0 and y 0); else if (z 0) System.out.println(x 0); 1、 x 0 and y 0; 2、 x 0; 3、 x 0 and z = 100) System.out.println(too hot); else if (temperature 0 & x 0) & (x 0 | x 0) | (x 0 | x 10 & y 0 | (x 10 & y 0 | x 10 & y 0 | x 10) & y 0) 答案 1 2 3 第 54题 How many times will the following code print Welcome to Java? int count = 0; while (count 10) System.out.println(Welcome to Java); count+; 1、 8 2、 9 3、 10 4、 11 5、 0 答案 3 第 55题 Analyze the following code. int count = 0; while (count 100) / Point A System.out.println(Welcome to Java!); count+; / Point B / Point C 1、 count 100 is always true at Point A 2、 count 100 is always true at Point B 3、 count 100 is always false at Point B 4、 count 100 is always true at Point C 5、 count 100 is always false at Point C 答案 1 5 第 56题 How many times will the following code print Welcome to Java? int count = 0; do System.out.println(Welcome to Java); while (count+ 10); 1、 8 2、 9 3、 10 4、 11 5、 0 答案 4 第 57题 What is the value in count after the following loop is executed? int count = 0; do System.out.println(Welcome to Java); while (count+ 9); System.out.println(count); 1、 8 2、 9 3、 10 4、 11 5、 0 答案 3 第 58题 Do the following two statements in (I) and (II) result in the same value in sum? (I): for (int i = 0; i10; +i) sum += i; (II): for (int i = 0; i10; i+) sum += i; 1、 Yes 2、 No 答案 1 第 59题 Is the following loop correct? for (; ; ); 1、 Yes 2、 No 答案 1 第 60题 Analyze the following code: public class Test public static void main (String args) int i = 0; for (i = 0; i 10; i+); System.out.println(i + 4); 1、 The program has a compile error because of the semicolon (;) on the for loop line. 2、 The program compiles despite the semicolon (;) on the for loop line, and displays 4. 3、 The program compiles despite the semicolon (;) on the for loop line, and displays 14. 4、 The for loop in this program is same as for (i = 0; i 4) break; while (item 5); 1、 5 2、 6 3、 7 4、 8 答案 2 第 63题 After the continue outer statement is executed in the following loop, which statement is executed? outer: for (int i = 1; i 10; i+) inner: for (int j = 1; j 50) continue outer; System.out.println(i * j); next: 1、 The control is in the outer loop, and the next iteration of the outer loop is executed. 2、 The control is in the inner loop, and the next iteration of the inner loop is executed. 3、 The statement labeled next. 4、 The program terminates. 答案 1 第 64题 Suppose the input for number is 9. What is the output from running the following program? import java.util.Scanner; public class Test public static void main(String args) Scanner input = new Scanner(System.in); System.out.print(Enter an integer: ); int number = input.nextInt(); int i; boolean isPrime = true; for (i = 2; i 0) System.out.print(message); n-; What is the printout of the call nPrint( a , 4)? 1、 aaaaa 2、 aaaa 3、 aaa 4、 invalid call 答案 4 第 70题 Suppose static void nPrint(String message, int n) while (n 0) System.out.print(message); n-; What is k after invoking nPrint(A message, k)? int k = 2; nPrint(A message, k); 1、 0 2、 1 3、 2 4、 3 答案 3 第 71题 Analyze the following code: public class Test public static void main(String args) System.out.println(xMethod(5, 500L); public static int xMethod(int n, long l) System.out.println(int, long); return n; public static long xMethod(long n, lon