Java教学资料（华南理工大学）review.docVIP

1、Identify and correct the errors in the following program: public class Exe48 { public static method1(int n,m){ n += m; xMethod(3.4); } public static int xMethod(int n){ if (n0) return 1; else if (n==0) return 0; else return -1; } } 2、What is pass by value? Show the result of the following programs: public class exer4112 { public static void main(String[] args) { //Initialize times int times = 3; System.out.println(Before the call, + variable times is + times); //Invoke nPrintln and display times nPrintln(Welcome to Java!, times); System.out.println(After the call,+variable times is + times); } //Print the message n times public static void nPrintln(String message, int n){ while (n 0){ System.out.println(n = + n); System.out.println(message); n--; } } } 3、Show the output of the following program: public class Test { public static void main (String[] args) { int number = 0; int[] numbers = new int[1]; m(number, numbers); System.out.println(“numbers is “ + number +” and numbers[0] is “ + numbers[0]); } public static void m(int x, int[] y) { x = 3; y[0] = 3; } } 4、Which of the following statements are valid array declarations? int I = new int(30); double d[] = new double[30]; char[] r = new char(1..30); float f[] = {3, 4, 3, 2}; char[] c = new char(); int[][] r = new int[2]; 5、Describe the difference between passing a parameter of a primitive type and passing a parameter of a reference type. Show the output of the following program: 1. public class Test { public static void main(String[] args) { Count myCount = new Count(); Int times = 0; For (int I = 0; i100; i++) Increment(myCount, times); System.out.println(“count is “ + myCount.count); System.out.println(“times is “ + times); } Public static void increment ( Count c, int times) { c.count++; ti