I am trying to get this loop to ask the question again what the user inputs not a 1 or a 2 but it puts me in a infinite loop how do i get out?
package vga;
import java.util.Scanner;
public class FPS_Info {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
boolean placeHolder;
String gameList[] = new String[2];
gameList[0] = ("Battlefield 1");
gameList[1] = ("Call Of Duty WWII");
System.out.printf("Please slect from theses games %s or %s.%nType 1 for %s and type 2 for %s.%n",
gameList[0], gameList[1], gameList[0], gameList[1]);
int gameSelection = scanner.nextInt();
if (gameSelection == 1 || gameSelection ==2) {
placeHolder = true;
}
while (placeHolder = true) {
if (gameSelection == 1) {
System.out.println("Battlefield 1, good choice.");
break;
} else if (gameSelection == 2) {
System.out.println("Call Of Duty WWII, good selection.");
break;
} else {
System.out.println("Please enter one of the options.");
placeHolder = false;
}
}
}
}
If you restructure your code, you don't need the placeholder.
import java.util.Scanner;
public class FPS_Info {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
boolean placeHolder;
String gameList[] = new String[2];
gameList[0] = ("Battlefield 1");
gameList[1] = ("Call Of Duty WWII");
System.out.printf("Please slect from theses games %s or %s.%nType 1 for %s and type 2 for %s.%n",
gameList[0], gameList[1], gameList[0], gameList[1]);
int gameSelection = scanner.nextInt();
while (gameSelection != 1 && gameSelection != 2) { // or while (gameSelection > 0 && gameSelection <= gameList.length)
System.out.println("Please enter one of the options.");
gameSelection = scanner.nextInt();
}
if (gameSelection == 1) {
System.out.println("Battlefield 1, good choice.");
}
else if (gameSelection == 2) {
System.out.println("Call Of Duty WWII, good selection.");
}
}
}
Your code includes:
while (placeHolder = true)
You probably meant placeHolder == true. The = assigns true rather than checks against it, so it's not doing the loop like you probably meant.
That said, there's no reason to == true in the first place. You can just
while (placeHolder)
Related
I am new to JAVA. I don't understand why JAVA give me two souts.
(Input row & column (throw 1 space): Input row & column (throw 1 space): )
In the first pass, it does not wait for my input and think str = "". And in the second pass its waiting for my input.
Ssory, I forgot to tell that beforŠµ this block of code - my Scanner was opened. I asked program:
while (true) {
System.out.print("Enter game size (3 - 20): ");
if (SCAN.hasNextInt()) {
return SCAN.nextInt();
}
System.out.println(SCAN.next() + " - not a number!");
I think I should clear scanners buffer ( /n ). But I dont know how.
private static void humanTurn() {
System.out.println("HUMAN TURN");
String str;
String regex = "\\d{1,2}\\s\\d{1,2}";
Pattern myPattern = Pattern.compile(regex); // Pattern for checking
boolean checkPattern;
int x, y;
do {
do {
System.out.print("Input row & column (throw 1 space): ");
str = SCAN.nextLine();
Matcher myMatcher = myPattern.matcher(str);
checkPattern = myMatcher.matches();
} while (!checkPattern);
String[] strArr = str.split(" ");
x = Integer.parseInt(strArr[0]) - 1;
y = Integer.parseInt(strArr[1]) - 1;
} while (!isValidCell(x, y));
I have tried to guess your code. This is what I come up with. Still works fine. Let me know if anything else.
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
private static Scanner sc = new Scanner(System.in);
private static int size = 0;
public static void main(String[] args) {
size = getBoardSize();
humanTurn();
}
private static int getBoardSize() {
while (true) {
System.out.print("Enter game size (3 - 20): ");
if (sc.hasNextInt()) {
return sc.nextInt();
}
System.out.println(sc.next() + " - not a number!");
}
}
private static void humanTurn() {
System.out.println("HUMAN TURN");
String str;
String regex = "\\d{1,2}\\s\\d{1,2}";
Pattern myPattern = Pattern.compile(regex); // Pattern for checking
boolean checkPattern;
int x, y;
do {
do {
System.out.print("Input row & column (throw 1 space): ");
str = sc.nextLine();
Matcher myMatcher = myPattern.matcher(str);
checkPattern = myMatcher.matches();
} while (!checkPattern);
String[] strArr = str.split(" ");
x = Integer.parseInt(strArr[0]) - 1;
y = Integer.parseInt(strArr[1]) - 1;
} while (!isValidCell(x, y));
}
private static boolean isValidCell(int x, int y) {
return x < size && y < size && x >= 0 && y >= 0;
}
}
(The surface area of the ByteBuddy API is overwhelmingly enormous, which is why I'm asking the question.)
I'm aware that I can take a TypeDescription.Generic and determine its "sort" and proceed rather laboriously "by hand" from there, but often times I've found there is a method buried somewhere that will do this sort of tedious work for me.
EDIT: a commenter asked for the "tedious" recipe. Here it is (stand back; please note the various implementations of various Types are more or less what you'd expect them to be):
public static final Type toType(final TypeDefinition type) throws ReflectiveOperationException {
final Type returnValue;
if (type == null) {
returnValue = null;
} else {
final TypeDescription.Generic genericType = type.asGenericType();
switch (type.getSort()) {
case GENERIC_ARRAY:
returnValue = new DefaultGenericArrayType(toType(type.getComponentType()));
break;
case NON_GENERIC:
returnValue = Class.forName(type.getTypeName(), false, Thread.currentThread().getContextClassLoader());
break;
case PARAMETERIZED:
final TypeDefinition ownerType = genericType.getOwnerType();
final TypeDefinition rawType = type.asErasure();
final List<? extends TypeDefinition> actualTypeArguments = genericType.getTypeArguments();
if (actualTypeArguments == null || actualTypeArguments.isEmpty()) {
returnValue = new DefaultParameterizedType(toType(ownerType), toType(rawType));
} else {
final Type[] actualJavaTypeArguments = new Type[actualTypeArguments.size()];
for (int i = 0; i < actualTypeArguments.size(); i++) {
actualJavaTypeArguments[i] = toType(actualTypeArguments.get(i));
}
returnValue = new DefaultParameterizedType(toType(ownerType), toType(rawType), actualJavaTypeArguments);
}
break;
case VARIABLE:
final TypeVariableSource typeVariableSource = genericType.getTypeVariableSource();
final GenericDeclaration gd;
if (typeVariableSource instanceof TypeDefinition typeDefinition) {
gd = Class.forName(typeDefinition.asErasure().getTypeName(), false, Thread.currentThread().getContextClassLoader());
} else if (typeVariableSource instanceof MethodDescription.InDefinedShape methodDescription) {
// Reflection time
final String name = methodDescription.getName();
final Class<?> cls = Class.forName(methodDescription.getDeclaringType().asErasure().getTypeName(), false, Thread.currentThread().getContextClassLoader());
final List<? extends TypeDefinition> parameterTypes = methodDescription.getParameters().asTypeList();
final Class<?>[] parameterClasses = new Class<?>[parameterTypes.size()];
for (int i = 0; i < parameterTypes.size(); i++) {
parameterClasses[i] = Class.forName(parameterTypes.get(i).asErasure().getName(), false, Thread.currentThread().getContextClassLoader());
}
if (MethodDescription.CONSTRUCTOR_INTERNAL_NAME.equals(name)) {
assert TypeDescription.VOID.equals(methodDescription.getReturnType());
gd = cls.getDeclaredConstructor(parameterClasses);
} else {
assert !MethodDescription.TYPE_INITIALIZER_INTERNAL_NAME.equals(name);
gd = cls.getDeclaredMethod(name, parameterClasses);
}
} else {
throw new IllegalArgumentException("Unexpected type variable source: " + typeVariableSource);
}
final TypeVariable<?>[] typeVariables = gd.getTypeParameters();
TypeVariable<?> temp = null;
for (final TypeVariable<?> typeVariable : typeVariables) {
if (typeVariable.getName().equals(genericType.getSymbol())) {
temp = typeVariable;
break;
}
}
assert temp != null;
returnValue = temp;
break;
case VARIABLE_SYMBOLIC:
throw new IllegalArgumentException("Unexpected type: " + type);
case WILDCARD:
final List<? extends TypeDefinition> upperBounds = genericType.getUpperBounds();
final List<? extends TypeDefinition> lowerBounds = genericType.getLowerBounds();
if (lowerBounds == null || lowerBounds.isEmpty()) {
if (upperBounds == null || upperBounds.isEmpty() || (upperBounds.size() == 1 && TypeDescription.Generic.OBJECT.equals(upperBounds.get(0)))) {
returnValue = UnboundedWildcardType.INSTANCE;
} else {
// Upper bounded.
final Type[] upperJavaBounds = new Type[upperBounds.size()];
for (int i = 0; i < upperBounds.size(); i++) {
upperJavaBounds[i] = toType(upperBounds.get(i)); // XXX recursive
}
returnValue = new UpperBoundedWildcardType(upperJavaBounds);
}
} else {
assert upperBounds == null || upperBounds.isEmpty() || (upperBounds.size() == 1 && TypeDescription.Generic.OBJECT.equals(upperBounds.get(0))) : "Unexpected upper bounds: " + upperBounds + "; lower bounds: " + lowerBounds;
// Lower bounded.
assert lowerBounds.size() == 1 : "Unexpected size in lower bounds: " + lowerBounds;
returnValue = new LowerBoundedWildcardType(toType(lowerBounds.get(0))); // XXX recursive
}
break;
default:
throw new IllegalArgumentException("Unexpected type: " + type);
}
}
return returnValue;
}
No, you can only convert a Type to a TypeDescription.Generic but there is no option to do it the other way. The easiest option to emulate this would probably be to define a class that defines a field of the given Type, to load this class and to read the field type using Java reflection.
The reason Byte Buddy cannot convert a description to a Type is that Byte Buddy abstracts out class loaders and that type variables might be detached from their declaring source.
Am relatively new to java so I have no idea what the problem is. In my getter settings of this class, I'm trying to evaluate if the input is of integer 1, 2 or 3, then it will return one of the previously saved setters described here. I used the same conditional statements in the setter, but the getter tells me that my method needs to return type int. What am I doing wrong? Or should I be doing this a completely different way? lol.
public class AssignmentMarks {
private String courseName;
private int assignment1 = 0, assignment2 = 0, assignment3 = 0;
public AssignmentMarks(String name, int mark1, int mark2, int mark3){
//create constructor to use variables.
this.courseName = name;
this.assignment1 = mark1;
this.assignment2 = mark2;
this.assignment3 = mark3;
}
public void setMark(int assignmentNumber, int mark) {
//assign value of the assignments
if(assignmentNumber == 1) {
mark = this.assignment1;
}else if(assignmentNumber == 2) {
mark = this.assignment2;
}else if(assignmentNumber == 3){
mark = this.assignment3;
}
}
public int getMark(int assignmentNum) {
if(assignmentNum == 1) {
return assignment1;
}else if (assignmentNum == 2) {
return assignment2;
} else if (assignmentNum == 3) {
return assignment3;
}
}
}
public int getMark(int assignmentNum) {
if(assignmentNum == 1) {
return assignment1;
}else if (assignmentNum == 2) {
return assignment2;
} else if (assignmentNum == 3) {
return assignment3;
}
// in another case
throw new Exception("Assignment must be 1, 2 or 3);
}
for setter
public void setMark(int assignmentNumber, int mark) {
//assign value of the assignments
if(assignmentNumber == 1) {
// BAD mark = this.assignment1; don't set parameter is useless
this.assignment1=mark;
}else if(assignmentNumber == 2) {
// BAD mark = this.assignment2;
this.assignment2=mark;
}else if(assignmentNumber == 3){
// BAD mark = this.assignment3;
this.assignment3=mark;
}
// in another case
throw new Exception("Assignment must be 1, 2 or 3");
}
I don't remember if you must import Exception for throwing them.
if yes put import java.lang.Exception on top of your code.
your logic can be improved using arrays, but let's walk, and after you will running...
package LinkList2;
//import java.util.*;
public class Duplicates {
public static void removeDuplicates(LinkedListNode head)
{
LinkedListNode current = head;
while(current!= null && current.next!= null)
{
LinkedListNode curr = current;
while(curr!=null)
{
if(curr.next.data==current.data) //Getting error at this line
curr.next = curr.next.next;
else
curr = curr.next;
}
current = current.next;
}
}
public static void main(String args[])
{
LinkedListNode first = new LinkedListNode(0,null,null);
LinkedListNode head = first;
LinkedListNode second = first;
for(int i=1; i< 8; i++)
{
second = new LinkedListNode(i%2, null, null);
first.setNext(second);
second.setPrevious(first);
}
System.out.println(head.printForward());
removeDuplicates(head);// Getting error at this line
}
}
Getting null pointer exception in the above code. When I try to run the above code, it gives null pointer exception.
Please help me with my mistake.
Below is the implementation of LinkList where all the methods are defined
class LinkedListNode {
public LinkedListNode next;
public LinkedListNode prev;
public LinkedListNode last;
public int data;
public LinkedListNode(int d, LinkedListNode n, LinkedListNode p) {
data = d;
setNext(n);
setPrevious(p);
}
public void setNext(LinkedListNode n) {
next = n;
if (this == last) {
last = n;
}
if (n != null && n.prev != this) {
n.setPrevious(this);
}
}
public void setPrevious(LinkedListNode p) {
prev = p;
if (p != null && p.next != this) {
p.setNext(this);
}
}
public String printForward() {
if (next != null) {
return data + "->" + next.printForward();
} else {
return ((Integer) data).toString();
}
}
public LinkedListNode clone() {
LinkedListNode next2 = null;
if (next != null) {
next2 = next.clone();
}
LinkedListNode head2 = new LinkedListNode(data, next2, null);
return head2;
}
}
You are getting an exception just because of the following condition:
while(curr != null)
Replace it with while(curr != null && curr.next != null) this way you can check if you have the next element.
Hope this helps.
The problem is that here:
while(curr != null)
{
if(curr.next.data==current.data) //Getting error at this line
curr.next = curr.next.next;
else
curr = curr.next;
}
You are accessing the curr.next.data where you are not checking if that node is null or not. This through your NullPointerException.
To fix your problem is to check on the while loop, if the .next is also not null.
while(curr != null && curr.next != null)
{
if(curr.next.data==current.data) //Getting error at this line
curr.next = curr.next.next;
else
curr = curr.next;
}
In other words, you are not checking if your next node is actually the end of the linked list (i.e null). If you need in your program logic to handle this separately, then you should remove the check from the while loop, and implement this check differently.
I manage an Ivy repository with an extensive number of artifacts and i have been requested to list all third party librarys which we have a hundred odd. does anyone know of a a way to retrieve a list of artifacts from an ivy repo?
i found no such way to do this, i wrote a script in java to get the results, thought i might share the answer if people wanted it in the future, it is also formatted to be copied straight into an excel document.
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
public class ListArtifacts {
public static void main(String[] args) {
Collection<File> all = new ArrayList<File>();
addTree(new File("."), all);
String delimeter = "\\.";
List<String> remove = new ArrayList<String>();
List<String> everything = new ArrayList<String>();
remove.add("pom");
remove.add("jar");
remove.add("xml");
remove.add("txt");
remove.add("sha1");
remove.add("md5");
remove.add("metadata");
remove.add("tar");
remove.add("gz");
remove.add("zip");
remove.add("rar");
FileWriter fWriter = null;
BufferedWriter writer = null;
try {
fWriter = new FileWriter("info.txt");
writer = new BufferedWriter(fWriter);
Iterator itr = all.iterator();
while (itr.hasNext() == true){
String[] split;
String temp = itr.next().toString();
split = temp.split(delimeter);
int i = 0;
int j = 0;
boolean flag = false;
while (i < split.length){
while (j < remove.size()){
if (split[i].equals(remove.get(j))){
flag = true;
}
j++;
}
j = 0;
i++;
}
if (flag == false){
String output = "";
int k=0;
boolean flag2 = false;
boolean hasVersion = false;
while (k < split.length){
if (flag2 == true){
output += ".";
flag2 = false;
}
output = output + split[k].toString();
boolean lastInt = false;
try{
String last = split[k].substring(split[k].length() - 1);
if (isInteger(last) == true)
lastInt = true;
}catch(Exception e){}
if ((isInteger(split[k].toString()) == true) || (lastInt == true)){
flag2 = true;
hasVersion = true;
}
k++;
}
if (hasVersion == true){
everything.add(output.substring(1));
writer.append(output.substring(1));
writer.newLine();
}
}
}
int i = 0;
String delim = "\\\\";
String finalOutput = "";
String toSplit = "";
while (i < everything.size()){
toSplit = everything.get(i);
String[] split2 = toSplit.split(delim);
finalOutput = split2[0] + "\t";
int j = 1;
while (j < split2.length-2){
finalOutput += split2[j] + ".";
j++;
}
finalOutput += split2[split2.length-2] + "\t";
finalOutput += split2[split2.length-1];
writer.append(finalOutput);
writer.newLine();
i++;
}
writer.close();
} catch (Exception e) {
}
System.out.println(all);
}
public static boolean isInteger(String input )
{
try
{
Integer.parseInt(input);
return true;
}
catch(Exception e)
{
return false;
}
}
static void addTree(File file, Collection<File> all) {
File[] children = file.listFiles();
if (children != null) {
for (File child : children) {
all.add(child);
addTree(child, all);
}
}
}
}
im sure this can be done much more cleanly, but i did no higher thinking just did the first thing i thought of with no revision.
If you are looking to do this using ivy during a build, the report task should help you get a report of all the JARs you are using.
If you are trying to fetch these details from the repository manager (covering all possible users), could you answer the question from #oers? Repository managers often offer some API that you can use to get reports about the artifacts that they store.