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You can copy paste the below code into a file named Test.java and execute it. inside the main block you can see the if condition. check if the list is not null and then use the size parameter of the array list to check if it is empty.
import java.util.ArrayList;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ArrayList lst = new ArrayList();
if(lst != null && lst.size() == 0){
System.out.println("Array list is empty");
}
}
}
What else can I help you with?
What is java string?
array of character data type which is terminated by null character
How can i check a null at the end of an character array in java?
A character array, by nature, is a primitive-type data array. It can't contain a null value. You cannot cast a char as a null. char[] charArray = {'1','2','s',null}; //this doesn't compile. However, if you have an array of Character objects, then it's possible. Character[] charArray = {'1','2','s',null}; //this DOES compile A proposed algorithm is to initialize a test boolean as false, then use a for loop to iterate through the array. Set the flag to true (and break the loop) based upon whether one of the objects you run into is null. What you do from there is up to what the rest of your code says.
What is the difference between array and string of array?
When we declare an array of characters it has to be terminated by the NULL , but termination by NULL in case of string is automatic.
How can you initialize an array in Java?
If you refering to Object then String[] something=new String[2]; Here you have to remember that something only allocated space for 2 String object but it did not created them yet. By default Objects are intantiated to null so if you try to print the content of an array System.out.println(something[0]);//print null System.out.println(something[0].toLowerCase()); Throws NullPointerException Couple other ways to create Arrays In java String[] something=new String[]{"Me","You"}; String[] something={"Me", "You"};
How do you initialize an array variable in java program?
An array in java is a collection of items stored into a single unit. The array has some number of slots (elements), each slot in the array can hold an object or a primitive value. Arrays in java are objects that can be treated just like other objects in the languageArrays can contain any type of element value , but we can't store different types in a single array. We can have an array of integers or an array of strings or an array of arrays.To create an array in java ,use three steps1. Declare a variable to hold the array2. Create a new array object and assign it to the array variable3. Store things in that array
What is NULL array in C Language?
There is no "NULL array" as such, you may take a pointer to an array and set it to NULL (binary 0) e.g. int* foo; // Declare a pointer foo = malloc( 40 * sizeof(int)); //Allocate an array of 40 integers pointed to by "foo" foo = NULL; //Set the pointer to NULL, if you're using a garbage collector this should trigger an automatic free() of the memory allocated to the array. If you are NOT using a garbage collector (which is more common in C) this line is a memory leak.
Java does not support pointers then what is null pointer exception?
A null pointer exception is thrown when you are trying to manipulate an object that is null. It is just the name and does not have any relevance to the pointers as in C Example: ArrayList lst = null; Object obj = lst.get(0); In the first line we have declared an array list. Without initializing it we have tried to access the element in the 0th position. This would cause a null pointer exception.
How do you set the null value in array?
Depends on the programming language, some languages may have already initialize an array with null (or the default value of the type), some of them require explicitly assignments by stepping through each element of that array, and assigning them with null. (imperative languages)
Why is c string defined as an array?
Every programming language treats strings as arrays. A C string is defined as being a null-terminated array of characters. A C string that does not have a null-terminator is just an array of character values, but without a null-terminator the onus is upon the programmer to keep track of the array's length.
Delete an element from an options array?
Set it to null
Java null pointer exceptions?
A null pointer exception in java comes when you are trying to perform any action on an object that isnt initialized/has a value i.e., is a NULL Value Ex: private String s; //declare a string if(s.equals("test")){ //do something.. } You will get a null pointer in the if condition because you are checking a value that is null which is not allowed..
Does null vector have real existence?
No. But then can you prove that you do?
