java generics: can't create a simple print array method

java generics: can't create a simple print array method

By : user2953205
Date : November 20 2020, 01:01 AM
this will help When it comes to generics, Java makes a difference between primitive types and types derived from java.lang.Object. Only non-primitive types can be used as arguments of generic methods. Since int is not generic, printArray does not apply to it.
You can fix it by providing an overload for int, or by making integerArray an Integer[]:
code :
Integer[] integerArray = {1,2,3,4,5};

Share : facebook icon twitter icon
Java Arraylist.Using Generics and Wildcards to create a reusable method

Java Arraylist.Using Generics and Wildcards to create a reusable method

By : Seng Santphallin
Date : March 29 2020, 07:55 AM
around this issue I am creating a reusable method that returns an array-list. , Try this :
code :
public abstract class TypeBase {


public class TypeOne extends TypeBase {
    public TypeOne(String val1, String val2) {
        // TODO Auto-generated constructor stub

public class TypeTwo extends TypeBase {
    public TypeTwo(String val1, String val2, int val3, boolean val4) {
        // TODO Auto-generated constructor stub

public <T extends TypeBase> List<T> getReusable(int method) {
    List<T> mResuableList = new ArrayList<T>();
    switch (method) {
    case 1:
        mResuableList.add((T) new TypeOne("TypeOne", "TypeOneID"));
    case 2:
        mResuableList.add((T) new TypeTwo("TypeTwo", "TypeTwoID", 1234, true));
    return mResuableList;

public class UsingClass{
    public void callReusable(){
        List<TypeOne> lstOne = getReusable(1);
        List<TypeTwo> lstTwo = getReusable(2);
Java Generics: create a general method operating on parent classes

Java Generics: create a general method operating on parent classes

By : user3340782
Date : March 29 2020, 07:55 AM
it should still fix some issue the problem here is that Java does not allow downcasting. You should create new Objects of the childclasses instead of returning new Objects of the parent class.
The parseERType Method should look something like this:
code :
HERMEntityRelationshipType parseERType(DBMEntityRelationshipType   dbmERType){
    if(dbmERType.getClass().equals(DBMEntityType.class)) {
        return new HERMEntityType(dbmERType);
    } else {
        return new HERMRelationshipType(dbmERType);

How Can I create method which use Java generics put the maps key to list?

How Can I create method which use Java generics put the maps key to list?

By : Kiairus Diamond
Date : March 29 2020, 07:55 AM
Does that help , Maybe your map is empty, because the example below works:
code :
public class Utils {

    public <T, K> List<T> map2list(Map<T, K> map) {
        List<T> list = new ArrayList<T>(map.keySet());
        return list;

     * @param args
    public static void main(String[] args) {
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("test1", 1);
        map.put("test2", 2);
        map.put("test3", 3);
        Utils t = new Utils();
        List<String> result = t.map2list(map);
        for (String key : result) {

How to create an ensureCapacity method that deals with Array Generics in Java

How to create an ensureCapacity method that deals with Array Generics in Java

By : David
Date : March 29 2020, 07:55 AM
I wish this help you So, I am creating a generic data structure named "Sack". In this I add items to a sack, grab a random item, see if it's empty, or dump out its contents etc. Also I'm creating it to expand to hold as many items as needed. , I figured it out, here's what the solution is to my question.
code :
private void ensureCapacity(int capacity)
    if (elementData.length < capacity)
        int newCapacity = elementData.length * 2 + 1;
        elementData = Arrays.copyOf(elementData, newCapacity);
How to create a grab method in Java that deals with Generics and Arrays

How to create a grab method in Java that deals with Generics and Arrays

By : user2486922
Date : March 29 2020, 07:55 AM
I wish did fix the issue. I don't understand why your grab method returns an array instead of a single element. I can suggest you a different approach
code :
public class Sack<E> {
    private final static int DEFAULT_CAPACITY = 10;
    private final static float REALLOC_FACTOR = 1.5f;
    private E[] elementData;
    private int size;

    public Sack() {
    public Sack(int capacity) {
        if(capacity <= 0)
            throw new IllegalArgumentException("capacity " + capacity);
        elementData = (E[]) new Object[capacity];
    public boolean isEmpty() {
        return size == 0;
    public void add(E item) {
        int index = size++;
        if(size > elementData.length-1)
            elementData = Arrays.copyOf(elementData, (int)(size*REALLOC_FACTOR));
        elementData[index] = item;
    public E [] dump() {
       E [] E2 = Arrays.copyOf(elementData, size);
       Arrays.fill(elementData, null);
       size = 0;
       return E2;
    public E grab() {
        if(size == 0)
            return null;
        int index = (int)(Math.random()*size);
        E element = elementData[index];
        elementData[index] = elementData[size-1];
        elementData[size-1] = null;
        return element;
Related Posts Related Posts :
  • Stream corrupted exception - invalid code type AC [java]
  • Routing Sysout values to JTextArea
  • GWT RPC serialization for Dynamic Host Page
  • Best Approch of Returning Value from 'getter' Method
  • Understanding xml schemalocation
  • Checking if a PDF is PDF/A 1-a format or not using PDFBOX in java
  • Difference Between Variable and Identifier
  • How to compute two aggregate functions with Java streams?
  • Parse the value of the json to baseadapter in android?
  • JavaFX animation on raspberry pi
  • Solve "unchecked warning" in Java avoiding @suppressWarnings
  • How to specify a new name for a file while moving it to another directory in Java?
  • Popup window not showing up with spinner item selection?
  • how to iterate through json objects in java
  • Caused by: java.lang.NoClassDefFoundError: org/springframework/aop/framework/AbstractAdvisingBeanPostProcessor
  • Getting NoClassDefFoundError while running PMD task from Gradle
  • Matlab drag and drop file from windows explorer to figure (gui)
  • How does scala's actor model make use of C threads and native system threads?
  • Store java.util.Date as key in a Map based on reference equality instead of "value" equality
  • Error when logging into FTP from AsyncTask class using org.apache.commons.net.ftp.FTPClient
  • creating unique index in mongoDB
  • hibernate Query to find record based on substring
  • How many strings are in jvm string pool intern
  • Unable to initialize native-platform. on Jenkins
  • How to create a list of dummy files in Java?
  • Docker: Which approach is better? WAR embedded in image or base image + war?
  • java.lang.InternalError: CallerSensitive annotation expected at frame 1
  • How to write a method to read JSON files of different structures and return different POJO objects in Java?
  • Reference to Classes in Java
  • Unable to call function via companion object
  • REST: convert XML content passed with POST to a java object, attribute inside the element
  • Device not receive message from GCM
  • How to increase Openfire concurrent connection limit?
  • Android send custom parameter on AsyncTask
  • GWT - Get dom element's value from another page
  • How can i initialize an array in Java?
  • Is it possible to increase a java process's(when is running) size?
  • Getting Node Address instead of Value in Binary Search Tree
  • PdfByteContent not adding in iText pdf
  • Spring JpaRepository: delete() with subsequent save() in the same transaction
  • producer-consumer using arraydeque working only in breakpoint
  • Adding a JPanel to another JPanel
  • Comparison with operator ==, how does it work?
  • Error buildling with maven for openshift
  • What is the java equivilant to MySQL's smallint
  • proxy trouble on eclipse with https
  • Spring-Jdbc Template and Prepared statement
  • Mule - exception in Outbound endpoint Message payload is of type: byte[]
  • Modify package names for java classes generated from wsdl
  • How to download multiple images and have one progressBar using AsynTask (Android)
  • Implementing Service Provider, IdP and user in java with SAML (POC)
  • Why does my scanner repeat?
  • Can I forget ResultSetFuture in Cassandra java driver without facing memory leak?
  • XML to JAXB binding having nested elements?
  • Java: ToString() prints the same hashcode each time
  • Why am I getting a thread exception in my graphics program?
  • Can we read 4th byte from hexadecimal value?
  • How to create watermark in image just like Google maps watermarks
  • how come Thread class called inside another class?
  • AssertionError: Unexpected schema version 0: Unexpected schema version 0
  • shadow
    Privacy Policy - Terms - Contact Us © ourworld-yourmove.org