How to find length of a string array

Question

I am having a problem with the following lines where car is a String array which has not been initialized has no elements   String car     System out println car length     What is a possible solution

User · Answer

Well  in this case the car variable will be null  so dereferencing it  as you do when you access car length  will throw a NullPointerException   In fact  you can t access that variable at all until some value has definitely been assigned to it - otherwise the compiler will complain that  variable car might not have been initialized    What is it you re trying to do here  it s not clear to me exactly what  solution  you re looking for

User · Answer

In Java  we declare a String of arrays  eg  car  as  String   car  String car      We create the array using new  operator and by specifying its type -  String   car new String    String car   new String      This assigns a reference  to an array of Strings  to car  You can also create the array by initializing it -  String   car   Sedan   SUV   Hatchback   Convertible      Since you haven t initialized an array and you re trying to access it  a NullPointerException is thrown

User · Answer

This won t work  You first have to initialize the array  So far  you only have a String   reference  pointing to null   When you try to read the length member  what you actually do is null length  which results in a NullPointerException

User · Answer

Since car has not been initialized  it has no length  its value is null  However  the compiler won t even allow you to compile that code as is  throwing the following error  variable car might not have been initialized   You need to initialize it first  and then you can use  length   String car     new String      BMW    Bentley     System out println car length     If you need to initialize an empty array  you can use the following   String car     new String           or simply String car          System out println car length     If you need to initialize it with a specific size  in order to fill certain positions  you can use the following   String car     new String 3      initialize a String   with length 3 System out println car length      3 car 0     BMW   System out println car length      3   However  I d recommend that you use a List instead  if you intend to add elements to it   List lt String gt  cars   new ArrayList lt String gt     System out println cars size        0 cars add  BMW    System out println cars size        1

User · Answer

String car       is a reference to an array of String-s  You can t see a length because there is no array there

User · Answer

As all the above answers have suggested it will throw a NullPointerException   Please initialise it with some value s  and then you can use the length property correctly  For example   String   str      plastic    paper    use    throw     System out println  Length is       str length     The array  str  is now defined  and so it s length also has a defined value

User · Answer

I think you are looking for this  String   car   new String 10   int size   car length

User · Answer

Since you haven t initialized car yet so it has no existence in JVM Java Virtual Machine  so you have to initialize it first    For instance    car   new String  Porsche   Lamborghini      Now your code will run fine   INPUT   String car     car   new String  Porsche   Lamborghini    System out println car length     OUTPUT   2

[java] How to find length of a string array?

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