Java练习题1(有答案).doc

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、 Welcome to Java );
2、 "Welcome to Java");
3、 System.println( Welcome to Java );
4、 Welcome to Java );
5、 "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 ;
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

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++; "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; "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;
"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
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、 ;
2、 ;
3、 ; 4、 + " "); 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 ; public class Test1 {
public static void main(String[] args) { Scanner input = new Scanner(System.in); "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
;
}
}
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);

7

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)
"x > 0 and y > 0"); else if (z > 0)
"x < 0 and z > 0");
1、 x > 0 and y > 0;
2、 x < 0 and z > 0;
3、 x < 0 and z < 0;
4、 no printout.
答案 2 第 42题 Analyze the following code.
boolean even = false; if (even) {
"It is even!");
}
1、 The code displays It is even!
2、 The code displays nothing.
3、 The code is wrong. You should replace if (even) with if (even == true)
4、 The code is wrong. You should replace if (even) with if (even = true) 答案 2
第 43题 The following code displays ___________.
double temperature = 50; if (temperature >= 100) "too hot"); else if (temperature <= 40) "too cold"); else
"just right");
1、 too hot
2、 too cold
3、 just right
4、 too hot too cold just right 答案 3 第 44题 Analyze the following code:
Code 1:
boolean even; if (number % 2 == 0) even = true; else even = false; Code 2:
boolean even = (number % 2 == 0); 1、 Code 1 has compile errors.
2、 Code 2 has compile errors.
3、 Both Code 1 and Code 2 have compile errors.
4、 Both Code 1 and Code 2 are correct, but Code 2 is better. 答案 4 第 45题 The __________ method immediately terminates the program.
1、 System.terminate(0);
2、 System.halt(0);
3、 System.exit(0); 4、 System.stop(0); 答案 3 第 46题 What is the printout of the following switch statement?
char ch = a ; switch (ch) { case a : case A :
; break; case b : case B :
; break; case c : case C :
; break; case d : case D :
;
}
1、 abcd
2、 a
3、 aa
4、 ab 5、 abc 答案 2 第 47题 What is the printout of the following switch statement?
char ch = b ; switch (ch) { case a :
; case b :
; case c :
; case d :
;
}
1、 abcd
2、 bcd
3、 b
4、 bb
5、 bbb 答案 5 第 48题 Analyze the following program fragment: int x; double d = 1.5; switch (d) { case 1.0: x = 1; case 1.5: x = 2; case 2.0: x = 3;
}
1、 The program has a compile error because the required break statement is missing in the switch statement.
2、 The program has a compile error because the required default case is missing in the switch statement.
3、 The switch control variable cannot be double.
4、 No errors.
答案 3

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第 49题 Analyze the following code fragments that assign a boolean value to the variable even.
Code 1: if (number % 2 == 0) even = true; else even = false; Code 2:
even = (number % 2 == 0) ? true: false; Code 3: even = number % 2 == 0;
1、 Code 2 has a compile error, because you cannot have true and false literals in the conditional expression.
2、 Code 3 has a compile error, because you attempt to assign number to even.
3、 All three are correct, but Code 1 is preferred.
4、 All three are correct, but Code 2 is preferred. 5、 All three are correct, but Code 3 is preferred.
答案 5 第 50题 The statement "%3.1e", 1234.56) outputs ___________.
1、 0.1e+04
2、 0.123456e+04
3、 0.123e+04
4、 1.2e+03 5、 1.23+03 答案 4 第 51题 Analyze the following code: int i = 3434; double d = 3434;
"%5.1f %5.1f", i, d);
1、 The code compiles and runs fine to display 3434.0 3434.0.
2、 The code compiles and runs fine to display 3434 3434.0.
3、 i is an integer, but the format specifier %5.1f specifies a format for double value. The code has an error.
答案 3 第 52题 What is the value of the following expression?
true || true && false
1、 true
2、 false 答案 1 第 53题 Which of the following statements are true? 1、 (x > 0 && x < 10) is same as ((x > 0) && (x < 10))
2、 (x > 0 || x < 10) is same as ((x > 0) || (x < 10))
3、 (x > 0 || x < 10 && y < 0) is same as (x > 0 || (x < 10 && y < 0))
4、 (x > 0 || x < 10 && y < 0) is same as ((x > 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) {
"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
"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 {
"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 {
"Welcome to Java");
} while (count++ < 9);
;
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; i<10; ++i) { sum += i;
} (II): for (int i = 0; i<10; 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++); + 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 < 10; i++) { }; + 4); 答案 3 4

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第 61题 To add 0.01 + 0.02 + ... + 1.00, what order should you use to add the numbers to get better accuracy?
1、 add 0.01, 0.02, ..., 1.00 in this order to a sum variable whose initial value is 0.
2、 add 1.00, 0.99, 0.98, ..., 0.02, 0.01 in this order to a sum variable whose initial value is 0.
答案 1 第 62题 What is sum after the following loop terminates?
int sum = 0; int item = 0; do { item++; sum += item; if (sum > 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 exec