Thread: Im very new to java And switch statements

Hello everyone,

Its my first time posting here and im very thankful for the work you guys do here

Heres a java assignment i just received from my class and i think i did some of it right.
Can someone please tell me why this wont compile properly.

import java.io.*;
class Question07{
 
	public static void main(String args[]) throws IOException{
 
	BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
 
	System.out.println("Enter GPA : ");
	double gpa = Double.parseDouble(stdin.readLine());
 
 
 
		if(gpa>=3.5){
			int a = 1;
		}else if(gpa>=3.49 & gpa >= 3.00){
			int a = 2;
		}else if(gpa>=2.99 & gpa>=2.5){
			int a = 3;
		}else if(gpa>=2.49 & gpa>=2.00){
			int a = 4;
		}else if(gpa<2.0){
			int a = 5;
		}else{
			break;
		}	
			int x = a;
 
			switch(x){
 
			case (1):
			System.out.println("First Class\n");
			break;
 
			case(2):
			System.out.println("Upper second class\n");
			break;
 
			case(3):
			System.out.println("Lower secodn class\n");
			break;
 
			case(4):
			System.out.println("Pass\n");
			break;
 
			case(5):
			System.out.println("Fail\n");
			break;
 
			default:
			System.out.println("Invalid GPA\n");
 
 
		}
 
	}
 
}

Its good if someone can tell me what iv done wrong and how to correct it with good visual example.I just dont seem to have a good time with java

Thanks in advance

This portion looks fudged up to me. You should revise it. First off your using a bit-wise operator to compare the expressions in your if statements. You should be using &&. Secondly, if gpa == 4.0, wouldn't all your else-if's expressions be true? You should format it so only one expression is true at a time.

              int a = 0;  //Initialize outside of if-loop
                 if(gpa>=3.5){
			a = 1;
		}else if(gpa <= 3.49 && gpa >= 3.00){
			a = 2;
		}else if(gpa <=2.99 && gpa >= 2.5){
			a = 3;
		}else if(gpa <=2.49 && gpa >=2.00){
			a = 4;
		}else if(gpa < 2.0)
			a = 5;
		}else{
			break;
		}
                        switch(a){   //You don't need to assign it to another variable
                                        }

Also revise where you are allowed to use the 'break' statement.

Here is my take on it, hope it helps.

- Moved int a outside the loop.

- Removed the "break;" statement that was in the last else statement, and replaced it with a = -1;. I also added"(gpa<2.0 && gpa >= 0)" in the statement where a = 5 to enable to last else to get valid when you input a number below 0. This way, the last "default" switch will let you know you inputted an invalid number.

I must admit I am new to java as well, but I have found that trying to help other newbies helps me as well

import java.io.*;
class test{
 
	public static void main(String args[]) throws IOException{
 
	BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
 
	System.out.println("Enter GPA : ");
	double gpa = Double.parseDouble(stdin.readLine());
 
	int a;
 
		if(gpa>=3.5){
			a = 1;
		}else if(gpa>=3.49 & gpa >= 3.00){
			a = 2;
		}else if(gpa>=2.99 & gpa>=2.5){
			a = 3;
		}else if(gpa>=2.49 & gpa>=2.00){
			a = 4;
		}else if(gpa<2.0 && gpa >= 0){
			a = 5;
		}else{
			a = -1;
		}	
			int x = a;
 
			switch(x){
 
			case (1):
			System.out.println("First Class\n");
			break;
 
			case(2):
			System.out.println("Upper second class\n");
			break;
 
			case(3):
			System.out.println("Lower secodn class\n");
			break;
 
			case(4):
			System.out.println("Pass\n");
			break;
 
			case(5):
			System.out.println("Fail\n");
			break;
 
			default:
			System.out.println("Invalid GPA\n");
 
 
		}
 
	}
 
}

Firstly is a switch sequence necessary at all? --- Unless it's actually mentioned in the assignment? (can u post the wording please)

Also, have you checked the program logic by entering some gpa's? Enter 2.1 and tell us the result.