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I need the input of the user to not skip the value 100

I'm currently working on a program for an O Level project where I have chosen to make a class management system. In my method class, I have various methods which control different functions of my program, such as one which collects the name of the students or one which displays a histogram of the student's grades. However, I have discovered a flaw in one of my methods. This is the method that lists the names of the students, one by one (which are saved in an array from a method that is executed before this method) and asks for the students marks. Here, the user is able to enter any number, which is inconvenient, considering that numerical grades normally range from 0-100. I have tried the following code but I have reached a predicament. The code does in fact stop the user from entering a mark over 100, but instead of allowing the user to re-enter a correct mark, it skips over to the next student, leaving the previous student without a mark. The following is said code:
//mark input
public void markin() {
System.out.println("=====================================");
System.out.println("Please enter the mark of the students");
System.out.println("=====================================");
for (int g = 0; g != marks.length; g++) {
System.out.println(names[g]);
marks[g] = Keyboard.readInt();
while(marks[g]<0||marks[g]>100){
System.out.println("Kindly enter a number that is less than 100");
break;
}
}
}
Help would be very much appreciated and thank you in advance :)
Apologies if my English is not very good.

You almost got it - you need to read in your while-loop instead of breaking without reading. Also a do-loop would be more appropriate for not having to set an initial invalid value.
//mark input
public void markin() {
System.out.println("=====================================");
System.out.println("Please enter the mark of the students");
System.out.println("=====================================");
for (int g = 0; g != marks.length; g++) {
System.out.println(names[g]);
do {
System.out.println("Kindly enter a number that is less than 100");
marks[g] = Keyboard.readInt();
} while(marks[g]<0||marks[g]>100);
}
}

Set marks[ g ] to a number that isn't allowed before the loop, like - 1 then check the keyboard input inside of the while loop,
(and set It there every time as long as the while loop isn't stopped,
marks[g] = Keyboard.readInt();
and don't break the loop, as the loop would end anyways when the input is valid

The valid answers has to get into the array sequentially.
Use this simple trick to reset index [g] to the previous value
then you will overwrite the marks[g] value until you get a valid one:
while(marks[g]<0||marks[g]>100){
System.out.println("Kindly enter a number that is less than 100");
g--; // Resetting index to previous value
break;
}

How to initialize a variable in a do while loop without passing the value until the loop has closed?

I've been writing a program that requires the input of a number between 1 and 4. In order to prevent input of numbers outside the range. However the variable keeps passing to another piece of code and causing the program to fail.
This is the do while loop:
do
{
System.out.println("Please enter a quarter number 1-4: ");
quarter = scanIn.nextInt();
}while((quarter > 5 ) && (quarter < 0));
This is the piece of code that runs the variable:
for (int n = ((quarter * 3)-3); n < (quarter*3); n++)
{
String sum = fmt.format(monthSales[n]);
System.out.printf("Sales for month %d: %s\n", n+1, sum);
}
This is the error that returns when incorrect input is entered:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -6
at lab4.Lab4.main(Lab4.java:57)
I have tried limiting the scope of "quarter" to only within the loop but then the while clause does not function. How can I prevent the variable from passing until the loop has closed?
p.s. This problem is part of an assignment and therefore I must use a do while loop.

I see one thing in your code:
The "do/while" condition seems to be wrong. If your intention is, as I understood, keep asking the user until s/he informs a valid quarter between 1 and 4, the condition should be something like
do {
// ...
} while (quarterNum < 1 || quarterNum > 4);
If I suppose that quarter receives the value of quarterNum in some code in between, the second part seems to be correct and the exception should only occurs if quarter is not a valid value (-1 to be exact). Fixing the do/while condition it will not be possible any more.
I don't see where limiting variable scopes could have anything with your issue. (and I don't even see what you mean by "prevent[ing] the variable from passing until the loop has closed").
I hope I could help you.

Couldnt find the Error in Guess Game Class

Okay, this is part of the full code of a guessing game.
public static void Game(){ //Second page of game with option of continue playing when guessed close enough to answer.
Scanner scan = new Scanner(System.in);
GuessingGame testgame=new GuessingGame();
testgame.Generator();
int num = testgame.GetGenNum();
//Produces a random number between 1 and 100 inclusive of 1 and 100
System.out.println("Guess the target integer which is between 1 and 100 inclusive");
int guess=scan.nextInt();
int difference=(guess-num);
while(guess!=num){
int yesCounter=0;
System.out.println("Guess again " +num+" "+difference);
guess=scan.nextInt();
difference=(guess-num);
///something wrong here, shouldnt repeat if difference too big
if(difference<=5||difference>=-5){ //something wrong with the condition, it says its close enough even tho it isnt.
while(yesCounter<1){
System.out.println("Close enough, do you want to keep Guessing? Y/N ");
yesCounter++;
String play = scan.nextLine();
//play=play1;
while(!(play.equalsIgnoreCase("y")))
{
if(play.equalsIgnoreCase("n")){
System.exit(1);
}
else{
if((play.equalsIgnoreCase("y"))){
invalid();
guess=scan.nextInt();
}
else{
Game(); ///TAKE note as it might restart the game with new random integer
}
}
}
}
}
}
output is:
.........................
Play? Y/N
y
Guess the target integer which is between 1 and 100 inclusive
50
Guess again 44 6
44
Close enough, do you want to keep Guessing? Y/N
Guess the target integer which is between 1 and 100 inclusive
..........................
the problem is, when user guess a number, the condition is if the difference between the guess and the generated number is 5 or smaller, tell user that its close enough, and ask if user wants to continue guessing, but the condition wasn't fulfilled and yet still runs, can someone help?

while(!(play.equalsIgnoreCase("y")))
{
if(play.equalsIgnoreCase("n")){
System.exit(1);
}
else{
if((play.equalsIgnoreCase("y"))){
invalid();
guess=scan.nextInt();
....
That isn't right, if((play.equalsIgnoreCase("y"))) can never be true, since the loop it is in, explicitely cannot be entered if it is true. That's where your problem is, it will always restart the game because it calls Game() in the else-branch. In short, this is what you do:
boolean _true = true;
while(! _true) {
if(_true) {
//impossible
}
else {
Game(); //ALWAYS
}
}
Since you tagged your question with homework, I will not give the full correction, but now you know where it goes wrong, you should be able to figure out what you need to change in order to advance :)

You mixed or and and (Note: The condition you used (difference<=5||difference>=-5) is always true.). You may use any of the following
if (difference<=5 && difference>=-5) { ... } # difference is 5 or less
or
if (difference<=-5 || difference>=5) { ... } # difference is 5 or more
Better readable if you use Math.abs(...) instead:
if (Math.abs(difference)<=5) { ... } # difference is 5 or less
and
if (Math.abs(difference)>=5) { ... } # difference is 5 or more
resp.

if(difference<=5||difference>=-5) This says if the difference is less than 5 or greater than -5. All numbers are less than 5 or greater than -5, so this is always true.
I'm assuming what you want is something like if(Math.abs(difference)<=5). This will tell you if the absolute value of your difference variable is less than or equal to 5.

Average of n numbers in java

Using loop I want to calculate the average of n numbers in Java and when user enters 0 the loop ends.
Here is the code that I have written:
public class start {
public static void main(String[] args) {
System.out.println("Enter an int value, the program exits if the input is 0");
Scanner input = new Scanner (System.in);
int h = 0;
while (input.nextInt() == 0){
int inp = input.nextInt();
int j = inp;
int i = 0;
h = j + i;
break;
}
System.out.println("The total is: "+ h);
}
}
Am I making any logical error?

Don't name the sum h, but sum.
The while-condition is wrong
Why do you use inp and j and i?
There is an unconditional break - why?
You talk about the average. Do you know what the average is?
Your output message is not about average - it is about the sum.

"Am I making any logical error?"
Yes. This looks like a homework problem so I won't spell it out for you, but think about what the value of i is, and what h = j + i means in this case.
You also need to be careful about calling input.nextInt(). What will happen when you call it twice each time through the loop (which is what you are doing)?

Homework, right?
Calling input.nextInt() in the while loop condition and also to fill in int inp means that each trip through the loop is reading two numbers (one of which is ignored). You need to figure out a way to only read one number per loop iteration and use it for both the == 0 comparison as well as for inp.
Additionally, you've done the right thing having h outside the while loop, but I think you're confusing yourself with j and i inside the loop. You might consider slightly more descriptive names--which will make your code much easier to reason about.

You need to keep a counter of how many numbers you read so you can divide the total by this number to get the average.

Edited the while loop:
while(true){
int e=input.nextInt();
if(e==0) break;
h+=e;
numberOfItems++;
}
Your original implementation called nextInt() twice, which has the effect of discarding every other number (which is definitely not what you intended to do).

Assuming that you asking the user only once, to enter and if the number if zero you simply want to display the average. you need a variable declared outside the while loop that will keep adding different numbers entered by the user, along with a second variable which track the number of cases entered by the user and keep incrementing itself by one till number is not zero as entered by the user. And as the user Enters 0, the loop will break and here our Average will be displayed.
import java.util.Scanner;
public class LoopAverage
{
public static void main(String[] args0)
{
Scanner scan = new Scanner(System.in);
System.out.println("Enter any Integer value : ");
int value = -1, sum = 0, count = 0;
while((value = scan.nextInt()) != 0)
{
count++;
sum = sum + value;
}
System.out.println("Average : " + (sum / count));
}
}
Hope that might help,
Regards

yes, oodles of logical errors.
your while loop condition is wrong, you're consuming the first value
you enter and unless that number is 0 you never enter the loop at all
i var has no purpose
you're breaking after one iteration
you're not calculating a running total
you're not incrementing a count for the average dividend
you're not calculating an average
This looks like you threw some code together and posted it. The most
glaring errors would have been found just by attempting to run it.
Some other things to consider:
Make sure to check for divide by 0
If you do an integer division, you might end up with an incorrect
average, as it will be rounded. Best to cast either the divisor or
dividend to a float
variable names should be helpful, get into the habit of using them

I recommend you to refer to the condition of "while" loop: if condition meets, what would the program do?
(If you know a little bit VB, what is the difference between do...until... and do...while...?)
Also, when you call scanner.nextInt(), what does the program do? For each input, how should you call it?
Last but not least, when should you use "break" or "continue"?
For the fundamentals, if you are in a course, recommend you to understand the notes. Or you can find some good books explaining details of Java. e.g. Thinking in Java
Enjoy learning Java.

Java boolean if question

I am making a lottery program where I am asking if basically they would like a quick pick ticket. The numbers for their ticket of course would be random since it is a quick pick but the first four numbers range from 0-9 while the fifth number only goes up to 0-4. I am trying to ask them to input a button such as either "1" for no or "2" for yes if they don't want one then it would skip this step. But I am doing the boolean part incorrectly though. Could someone help me out?
Here is an example
System.out.println("Do you want Quick pick, 1 for no or 2 for yes? The first four numbers is from a separate set of 0 to 9 and the fifth number is from a set of 0 to 4.");
QuickPick=keyboard.nextInt();
if((QuickPick==1)){
return false;
}
if((QuickPick==2)){
return true;
int n = (int)(Math.random()*9+0);
System.out.println("Your QuickPick numbers are: " + kickerNumbers + kickerPowerball);
}
I still haven't gotten around to making the line of code for the final number of 0-4, just the first four numbers, so I haven't forgotten that.

Your code for case 2 immediately does a return true; which ends the method (I assume this is in a method) right then and there. Your other lines don't get execute at all.
Consider using a switch() statement here, it'll make it easier to read:
switch(QuickPick)
{
case 1:
return false;
case 2:
int n = (int)(Math.random()*9+0); // Why is n here? You don't do anything with it?
System.out.println("Your QuickPick numbers are: " + kickerNumbers + kickerPowerball);
return true;
default:
// Uh oh - someone did something bad maybe just return false?
return false;
}
Also your code for case 2 is definitely wrong, you need to generate a total of five numbers, using bounds 0-9 for the first 4 and 0-4 for the last one. You'll want to use Java's Random to do this (not Math.Random) something like:
Random rand = new Random();
int somethingRandom = rand.nextInt(10);
// Will give you an integer value where 0 < val < 10
// You can call rand.nextInt as many times as you want
To avoid doing your homework for you -- I'll follow the typical CS textbook line and say "Implementation left as an exercise."

The code after return true will not be executed - you need to put that prior to the return statement

Like Marvo said, you dropped a brace in your if.
But you also have faulty logic. I'm not quite sure what the purpose of the method you're in is (that returns a boolean value). But your last few lines will never be reached unless the user types in something like 3 or 42.
Assuming the method is supposed to a) Ask if the user wants a Quick Pick b) Calculate the Quick Pick, if desired c) Return true/false depending on whether the Quick Pick happened or not, you should have:
public boolean doQuickPick()
{
System.out.println("Do you want Quick pick, 1 for no or 2 for yes? The first four numbers is from a separate set of 0 to 9 and the fifth number is from a set of 0 to 4.");
QuickPick=keyboard.nextInt();
if((QuickPick==1)){
return false;
}
if((QuickPick==2)){
int n = (int)(Math.random()*9+0);
System.out.println("Your QuickPick numbers are: " + kickerNumbers + kickerPowerball);
return true;
}
}
As a separate issue, it'd be much better style to break that into several methods. boolean yesNoPrompt(String message), generateQuickPick(), etc.
Your question is kind of unclear, so I'm afraid I can't be much more help than that. Do post any clarifications / further questions if you have them.

if((QuickPick==2)){
return true;
int n = (int)(Math.random()*9+0);
System.out.println("Your QuickPick numbers are: " + kickerNumbers + kickerPowerball);
}
In the above copied code from your question, I see that you will be getting compilation errors in your IDE. Your IDE will complain about "Unreachable Code" for the line that is just below the return statement. So, you need to put the return statement at the end of the if block.