Java Math.random won't refresh on while loop (of course) - java

So, I am trying to make a text based RPG. A good starter project, as I am new to all of this. I want to make a critical hit, and math.random seems like the best way to go. Only one problem; when it loops, it doesn't refresh the random. I can assume that that's because it calls it once, and once it's called in, that's it. That's it's value. I want to know of an alternative so it refreshes every time the while loop starts over. I know there are some other bugs in my code; but that's not what I'm focusing on right now. Here's the entire method:
public void battleStart(Enemy enemy, Player player)
{
while (enemy.health != 0)
{
String battle = null;
int criticalHt = (int) (Math.random() * 10) + 0;
boolean T = true;
while (T = true)
{
battle = Game.console.next();
enemy.attackplayer(player);
if (battle.toLowerCase().contains("skip"))
{
System.out.println(criticalHt);
if (criticalHt == 1)
{
player.hitPoints -= enemy.dmg * 2;
System.out.println(Game.toTitleCase(enemy.firstName) + " " + Game.toTitleCase(enemy.lastName) + " has used " + Game.toTitleCase(enemy.attackName) + " for a critical level of " + enemy.dmg * 2 + "!.\n Your health is now " + player.hitPoints + ".");
}
else
{
player.hitPoints -= enemy.dmg;
System.out.println(Game.toTitleCase(enemy.firstName) + " " + Game.toTitleCase(enemy.lastName) + " has used " + Game.toTitleCase(enemy.attackName) + ".\n Your health is now " + player.hitPoints + ".");
System.out.println("Your turn to attack! Use an attack, or type \"skip\" to let your enemy strike.");
};
if (battle.contains("skp"))
{
};
}
}
}

Move the code
int criticalHt = (int)(Math.random() * 10) + 0;
INSIDE the while loop
while(T = true){
int criticalHt = (int)(Math.random() * 10) + 0;
battle = Game.console.next();
...

Related

How to double a value of private int type field?

This is the code of method takeDamage in the class Enemy which is a superclass of class Vampire.
public void takeDamage(int damage) {
int remainingHitPoints = hitPoints - damage;
if (remainingHitPoints > 0) {
setHitPoints(remainingHitPoints);
System.out.println(name + " took " + damage + " damage and have " + remainingHitPoints + " HitPoint left" + "\n------------------------------------" );
} else {
this.lives = this.lives - 1;
System.out.println(name + " took " + damage + " damage" + "\n------------------------------------" + "\n" + name +" lost a life" + "\n------------------------------------");
if (lives > 0) {
System.out.println(name + " revived" + "\n------------------------------------");
setHitPoints(remainingHitPoints + damage);
} else {
System.out.println(name + " is dead now RIP" + "\n------------------------------------");
setHitPoints(0);
}
}
}
In the class Vampire I override the method takeDamge:
public void takeDamage(int damage) {
int inflictedDamage = damage/2;
int doubleHitPoints = getHitPoints()*2;
int remainingHitPoints = getHitPoints() - inflictedDamage;
int remainingLives = getLives() - 1;
if (remainingHitPoints > 0) {
setHitPoints(remainingHitPoints);
System.out.println(getName() + " took " + inflictedDamage + " damage(Vampire takes inflicted damage) and has " + remainingHitPoints + " HitPoint left" + "\n------------------------------------" );
} else {
setLives(remainingLives);
System.out.println(getName() + " took " + inflictedDamage + " damage(Vampire takes inflicted damage)" + "\n------------------------------------" + "\n" + getName() +" lost a life" + "\n------------------------------------");
if (remainingLives > 0) {
System.out.println(getName() + " revived and even got stronger!" + "\n------------------------------------");
setHitPoints(doubleHitPoints);
} else {
System.out.println(getName() + " is dead now RIP" + "\n------------------------------------");
setHitPoints(0);
}
}
}
What I intend to do is double the object's hitPoints which is originally set by the constructor.
When a Vampire object takes enough damage to die (in other words, when it loses its life), this method successfully doubles the object's hitPoints.
The problem happens (if I diagnosed right) when the Vampire object takes not enough damage to die.
setHitPoints(remainingHitpoints); gets executed and when the Vampire object takes enough damage to die, it doubles the object's remainingHitPoints not an original hitPoints.
I would like to fix this issue.
The hitPoints field has been declared as private inside the Enemy class so if I understood well the only way to modify the value of this field is by using getHitPoint method (getter) inside the Enemy class.
You need some place where the original hit points are stored.
If your Enemy class doesn't provide this information and you only need it in the Vampire class you could change the Vampire class along these lines:
public class Vampire extends Enemy {
private int originalHitPoints;
public Vampire() {
// ...
originalHitPoints = getHitPoints();
}
public void takeDamage(int damage) {
// ...
if (remainingLives > 0) {
System.out.println(getName() + " revived and even got stronger!" + "\n------------------------------------");
setHitPoints(originalHitPoints * 2);
}
// ...
}
}
If you want to double the hit points every time the Vampire dies you could change the code of takeDamage() like this:
public void takeDamage(int damage) {
// ...
if (remainingLives > 0) {
System.out.println(getName() + " revived and even got stronger!" + "\n------------------------------------");
originalHitPointes *= 2; // double the hit points
setHitPoints(originalHitPoints);
}
// ...
}

Euler Project - Work out the first ten digits of the sum of the following one-hundred 50-digit numbers

I know that it is a horrible question to ask at this forum since I do know the rules but at the moment I just do not know what the issue is here. So for anyone that has some spare time I would be very thankful if it could be answered. I tried to carry out the Euler Project exercise number 13: Work out the first ten digits of the sum of the following one-hundred 50-digit numbers.
I know the logic that I have used behind it is not the best and later I managed to solve the problem using another method, but it still bothers me until today why does the following code not work:
import java.util.ArrayList;
public class LargeSum {
public static ArrayList<String> addAll(ArrayList<ArrayList<Integer>> listOfResults) {
ArrayList<String> result = new ArrayList<String>();
int singlesum = 0;
int remainder = 0;
for (int i = 49; i >= 0; i--) {
System.out.println(remainder + "to rem");
singlesum += remainder;
for (ArrayList<Integer> list : listOfResults) {
System.out.println(list.get(i));
singlesum += list.get(i);
}
String lastChar = String.valueOf(singlesum);
singlesum = 0;
result.add(String.valueOf(lastChar.charAt(lastChar.length() - 1)));
remainder = 0;
if (lastChar.length() > 1) {
remainder = Integer.parseInt(lastChar.substring(0, lastChar.length() - 1));
}
}
if (remainder > 0)
result.add(String.valueOf(remainder));
return result;
}
public static ArrayList<ArrayList<Integer>> createLists() {
ArrayList<ArrayList<Integer>> results = new ArrayList<ArrayList<Integer>>();
String c =
"37107287533902102798797998220837590246510135740250"
+ "46376937677490009712648124896970078050417018260538"
+ "74324986199524741059474233309513058123726617309629"
+ "91942213363574161572522430563301811072406154908250"
+ "23067588207539346171171980310421047513778063246676"
+ "89261670696623633820136378418383684178734361726757"
+ "28112879812849979408065481931592621691275889832738"
+ "44274228917432520321923589422876796487670272189318"
+ "47451445736001306439091167216856844588711603153276"
+ "70386486105843025439939619828917593665686757934951"
+ "62176457141856560629502157223196586755079324193331"
+ "64906352462741904929101432445813822663347944758178"
+ "92575867718337217661963751590579239728245598838407"
+ "58203565325359399008402633568948830189458628227828"
+ "80181199384826282014278194139940567587151170094390"
+ "35398664372827112653829987240784473053190104293586"
+ "86515506006295864861532075273371959191420517255829"
+ "71693888707715466499115593487603532921714970056938"
+ "54370070576826684624621495650076471787294438377604"
+ "53282654108756828443191190634694037855217779295145"
+ "36123272525000296071075082563815656710885258350721"
+ "45876576172410976447339110607218265236877223636045"
+ "17423706905851860660448207621209813287860733969412"
+ "81142660418086830619328460811191061556940512689692"
+ "51934325451728388641918047049293215058642563049483"
+ "62467221648435076201727918039944693004732956340691"
+ "15732444386908125794514089057706229429197107928209"
+ "55037687525678773091862540744969844508330393682126"
+ "18336384825330154686196124348767681297534375946515"
+ "80386287592878490201521685554828717201219257766954"
+ "78182833757993103614740356856449095527097864797581"
+ "16726320100436897842553539920931837441497806860984"
+ "48403098129077791799088218795327364475675590848030"
+ "87086987551392711854517078544161852424320693150332"
+ "59959406895756536782107074926966537676326235447210"
+ "69793950679652694742597709739166693763042633987085"
+ "41052684708299085211399427365734116182760315001271"
+ "65378607361501080857009149939512557028198746004375"
+ "35829035317434717326932123578154982629742552737307"
+ "94953759765105305946966067683156574377167401875275"
+ "88902802571733229619176668713819931811048770190271"
+ "25267680276078003013678680992525463401061632866526"
+ "36270218540497705585629946580636237993140746255962"
+ "24074486908231174977792365466257246923322810917141"
+ "91430288197103288597806669760892938638285025333403"
+ "34413065578016127815921815005561868836468420090470"
+ "23053081172816430487623791969842487255036638784583"
+ "11487696932154902810424020138335124462181441773470"
+ "63783299490636259666498587618221225225512486764533"
+ "67720186971698544312419572409913959008952310058822"
+ "95548255300263520781532296796249481641953868218774"
+ "76085327132285723110424803456124867697064507995236"
+ "37774242535411291684276865538926205024910326572967"
+ "23701913275725675285653248258265463092207058596522"
+ "29798860272258331913126375147341994889534765745501"
+ "18495701454879288984856827726077713721403798879715"
+ "38298203783031473527721580348144513491373226651381"
+ "34829543829199918180278916522431027392251122869539"
+ "40957953066405232632538044100059654939159879593635"
+ "29746152185502371307642255121183693803580388584903"
+ "41698116222072977186158236678424689157993532961922"
+ "62467957194401269043877107275048102390895523597457"
+ "23189706772547915061505504953922979530901129967519"
+ "86188088225875314529584099251203829009407770775672"
+ "11306739708304724483816533873502340845647058077308"
+ "82959174767140363198008187129011875491310547126581"
+ "97623331044818386269515456334926366572897563400500"
+ "42846280183517070527831839425882145521227251250327"
+ "55121603546981200581762165212827652751691296897789"
+ "32238195734329339946437501907836945765883352399886"
+ "75506164965184775180738168837861091527357929701337"
+ "62177842752192623401942399639168044983993173312731"
+ "32924185707147349566916674687634660915035914677504"
+ "99518671430235219628894890102423325116913619626622"
+ "73267460800591547471830798392868535206946944540724"
+ "76841822524674417161514036427982273348055556214818"
+ "97142617910342598647204516893989422179826088076852"
+ "87783646182799346313767754307809363333018982642090"
+ "10848802521674670883215120185883543223812876952786"
+ "71329612474782464538636993009049310363619763878039"
+ "62184073572399794223406235393808339651327408011116"
+ "66627891981488087797941876876144230030984490851411"
+ "60661826293682836764744779239180335110989069790714"
+ "85786944089552990653640447425576083659976645795096"
+ "66024396409905389607120198219976047599490197230297"
+ "64913982680032973156037120041377903785566085089252"
+ "16730939319872750275468906903707539413042652315011"
+ "94809377245048795150954100921645863754710598436791"
+ "78639167021187492431995700641917969777599028300699"
+ "15368713711936614952811305876380278410754449733078"
+ "40789923115535562561142322423255033685442488917353"
+ "44889911501440648020369068063960672322193204149535"
+ "41503128880339536053299340368006977710650566631954"
+ "81234880673210146739058568557934581403627822703280"
+ "82616570773948327592232845941706525094512325230608"
+ "22918802058777319719839450180888072429661980811197"
+ "77158542502016545090413245809786882778948721859617"
+ "72107838435069186155435662884062257473692284509516"
+ "20849603980134001723930671666823555245252804609722";
for (int i = 0; i < 4950; i += 50) {
ArrayList<Integer> strings = new ArrayList<Integer>();
for (int j = i; j <= i + 49; j++) {
strings.add(Integer.parseInt(String.valueOf(c.charAt(j))));
}
results.add(strings);
}
return results;
}
public static void main(String[] args) {
ArrayList<ArrayList<Integer>> results = createLists();
System.out.println(addAll(results));
}
}
The array should give me the number from the back one by one each digit of the number yet I do not get the answer to the question. I investigated this many times for smaller numbers (where it worked) and for only two numbers (and it worked) yet I cannot get the answer to the question (I always get another number as result not the designated Result: 5537376230).
Thanks to everybody that looks at the code.
Best regards,
Rob
I believe the main source of the issue lies in the fact that you hardcoded a lot of numerical values and thus can not really verify correctness in the middle steps. Especially bad idea is using single String instead of the array of String[] for your source data.
Anyway, if you re-check the task you may find that the last numbers are:
...
72107838435069186155435662884062257473692284509516
20849603980134001723930671666823555245252804609722
53503534226472524250874054075591789781264330331690
while in your code you have:
+ "72107838435069186155435662884062257473692284509516"
+ "20849603980134001723930671666823555245252804609722";
So you just missed the last number and that spoils the result.
Sidenotes:
you don't really handle the top digits (your "top" digit is "55") properly which is a result of a lot of hardcoding but you probably already know that.
In java there is a BigInteger class that can solves this task easily. It is OK to write your own code for learning but for the real world task you should use a standard library unless you have a good reason not to use it.
In the case where you have a remainder left over, you add it to result as a string. But the digits in your results are reversed, so you also need to reverse the digits of the remainder.
It also looks like you've got an off-by-one error in the construction of your numbers. i < 4950 should be i < 5000 I think, since the 100th number starts at index 99 * 50 = 4950.

Java AVL Tree Problems

I'm trying to build an AVL tree in Java, but I'm having trouble with updating heights after the rotations. Here is the code I'm having trouble with.
public void checkHeights(Node<T> u) {
if (u == nil) return;
checkHeights(u.left);
checkHeights(u.right);
System.out.println(u.h);
if (height(u) != 1 + Math.max(height(u.left), height(u.right)))
throw new RuntimeException("Check heights shows incorrect heights");
int dif = height(u.left) - height(u.right);
if (dif < -1 || dif > 1)
throw new RuntimeException("Check heights found height difference of " + dif);
}
/**
* Fix up
* #param u
*/
public void fixup(Node<T> u) {
while (u != nil) {
int dif = height(u.left) - height(u.right);
if(debug)System.out.println("Node dif at " + u.x + " is: " + dif);
if (dif > 1) {
if(debug)System.out.println("u.left is larger");
if(height(u.left.left) - height(u.left.right) < 0) {
if(debug)System.out.println("u.left dif is: " + (height(u.left.left) - height(u.left.right)));
rotateLeft(u.left);
}
rotateRight(u);
} else if (dif < -1) {
if(debug)System.out.println("u.right is larger");
if(height(u.right.left) - height(u.right.right) > 0) {
if(debug)System.out.println("u.right dif is: " + (height(u.right.left) - height(u.right.right)));
rotateRight(u.right);
}
rotateLeft(u);
}
if(debug) System.out.println("Height of " + u.x + " is " + height(u));
u = u.parent;
}
}
public void rotateLeft(Node<T> u) {
super.rotateLeft(u);
u.h = Math.max(height(u.left), height(u.right)) + 1;
u.parent.h = Math.max(height(u.parent.left), height(u.parent.right)) + 1;
if(debug)System.out.println("After left rotation, " + u.x + " has height " + u.h + " and " + u.parent.x + " has height " + u.parent.h);
}
public void rotateRight(Node<T> u) {
super.rotateRight(u);
u.h = Math.max(height(u.left), height(u.right)) + 1;
u.parent.h = Math.max(height(u.parent.left), height(u.parent.right)) + 1;
if(debug)System.out.println("After right rotation, " + u.x + " has height " + u.h + " and " + u.parent.x + " has height " + u.parent.h);
}
I've done a bunch of unit tests, and I keep getting checkHeights throwing exceptions. I'm almost positive that what's going on is the when a rotation occurs at a depth greater than 2, the heights aren't updated recursively up the tree. For example, if I add values from 0 to 10 in, the first left rotation occurs no problem and the values get their right heights, but when I try to rotate lower down, the parent nodes aren't accurately update to their new heights, causing the exceptions to be thrown.
Any help would be greatly appreciated

Round Robin in Java

I am working on a round robin algorithm in Java, and I have a loop that is not working correctly. I believe it is a simple logic error that I am missing. The exec[] array holds execution times for processes in a cpu. I need the quantam to be subtracted from that time or the amount of time left if less than the quantam. Then I need it to check the next process. Each process should have one pass through until the execution time is 0. The sum makes sure that the statements keep running while there is any one process that needs to run. The sum is simply from adding all the array element times.
while (sum != 0) {
int show = i + 1;
if (exec[i] != 0 && exec[i] > quant) {
exec[i] = exec[i] - quant;
sum = sum - quant;
JOptionPane.showMessageDialog(null, "Process" + " " + show + " is at" + " " + exec[i]);
JOptionPane.showMessageDialog(null, "sum" + " " + " is " + sum);
if (i == irq - 1) {
i = 0;
} else {
i++;
}
}
if (exec[i] != 0 && exec[i] < quant) {
exec[i] = exec[i] - exec[i];
sum = sum - exec[i];
JOptionPane.showMessageDialog(null, "Process" + " " + show + " is at" + " " + exec[i]);
JOptionPane.showMessageDialog(null, "sum" + " " + " is " + sum);
if (i == irq - 1) {
i = 0;
} else {
i++;
}
}
}
Please let me know if there is a fix or if any more information is needed. Thanks!
exec[i]=exec[i]-exec[i];
sum=sum-exec[i];
Is same as
exec[i]=0;
sum=sum-0;
Also, you don't treat the case of exec[i]==quant
I am not sure, what you want to do. It sounds like "I want Multithreading to make my application faster" but within in Single-Core loop, you won't succeed.
If you want a CPU round robin, let the JVM (or the operating system) decide. Both are made for this:
Some kind of java pseudo-Code:
int threadPoolSize = Runtime.getRuntime().availableProcessors();
ExecutorService pool = Executors.newFixedThreadPool(threadPoolSize);
pool.execute(new ImplementationOfCallableOrRunnable());
http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/ExecutorService.html

Unkown Error Crashing a Server - Console Crashes too

Basically, whenever I type a certain command in a server, it loads all of this code multiple times (20+). For some reason whenever I type the command, the server freezes (including the console). If I stop the server and restart it, it says something is binded to the port the server is running on, resulting in me having to kill the server process. Is it because there are way too many calculations running at the time when I issue the command? I remember it didn't crash as much before, but after I changed how the percent bar was calculated, it crashes every time.
package com.mcvigor.utils;
import java.util.ArrayList;
import org.apache.commons.lang.WordUtils;
import org.bukkit.ChatColor;
import org.bukkit.inventory.meta.ItemMeta;
import com.mcvigor.RunePlayer;
import com.mcvigor.Skills;
public class ItemUtils {
public static ItemMeta addSkillInformation(ItemMeta i, Skills skill, RunePlayer rp) {
i.setDisplayName(ChatColor.GOLD + WordUtils.capitalize(skill.toString().toLowerCase()));
ArrayList<String> lore = new ArrayList<String>();
lore.add(ChatColor.RED + "Level " + ChatColor.YELLOW + rp.getSkillLevel(skill));
int xp = rp.getSkillXP(skill);
int neededXP = rp.getXPRequiredForLevel((rp.getSkillLevel(skill) + 1));
lore.add(ChatColor.RED + "Experience: " + ChatColor.YELLOW + xp + ChatColor.RED + " / " + ChatColor.YELLOW + neededXP);
lore.add(ChatColor.RED + "Remainder: " + ChatColor.YELLOW + (neededXP - xp));
float percent = (xp/neededXP);
int percent10 = (int) Math.floor(percent * 10);
String bar = "";
while (percent10 >= 10) {
bar += ChatColor.GREEN + "▀";
percent--;
}
while (percent10 < 10) {
bar += ChatColor.RED + "▀";
percent10--;
}
lore.add(ChatColor.RED + "Percent to next level: " + ChatColor.YELLOW + (int) percent + ChatColor.RED + "%");
lore.add(bar);
i.setLore(lore);
return i;
}
}
Edit:
Think its because of:
while (percent10 < 10) {
bar += ChatColor.RED + "▀";
percent10--;
}
percent10 will ALWAYS be less than 10 so it will keep on repeating.
You're testing a variable in a loop ending condition but that variable doesn't change in the loop :
while (percent10 >= 10) {
bar += ChatColor.GREEN + "▀";
percent--;
}
If percent10 is greater than 10 before the loop, you'll loop until there isn't enough memory to augment bar.
You probably should replace
percent--;
with
percent10--;
You have a similar problem in the loop just after :
while (percent10 < 10) {
bar += ChatColor.RED + "▀";
percent10--;
}
If percent10 is < 10, then it won't go bigger than 10 in the loop (apart in case of overflow).

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