Java exercise in the lab

1.  Follow the steps below:
     a) Create a new java project
     b) Create a class with name debug_test
     c) Copy the following fields in the debug_test class 
     
       import java.util.Random;
       public class debug_test {
       public static void main(String[] args) {
		double Sum,Sub,Mul,Div;
		int r1,r2;
		Random generator = new Random();
		for (int i=1;i<=4;i++)
                {	
                        r1 = generator.nextInt();
			r2=generator.nextInt();
			Sum=r1+r2;
			Sub=r1-r2;
			Mul=r1*r2;
			Div=r1/r2;
                 }
             }
       }
        
d) Use the debugger and fill in the table below:
          r1=
          r2=

iteration	Sum	Sub	Mul	Div
1				
2				
3				
4				


2. How many methods for rounding numbers are in the java.lang.math? (use www.javadoconline.com )

3. Use the sample program and write a simple phonebook with the following characteristics:
     a) First, the user enters the number of entities
     b) For each entity, the program asks about the name and the telephone number
     c) After the user enters all the names and telephone numbers, a window is displayed which 
       shows all the information (i.e., in each row : Name & Tel No)
     d) You should create two classes in your program: one for contact information and one 
        for your phonebook. 

You may need to have an array of objects in your program. For this purpose you can define them as following:

                        // example from sample program
                        
                        Student[] s=new Student[10];
                        for (int i=1;i<=10;i++)
	                    s[i]=Student();