How to get to a particular element in a List in java

Question

I have a CSV file  It has many lines  In each line there are multiple values separated by commas   I am using OPENCSV to extract data from the file  I want to have the ability to directly go to any particular line which is in List data structure   CSVReader reader   new CSVReader new FileReader                       myfile csv                 try                   List lt String   gt  myEntries   reader readAll                    for  String   s   myEntries                        System out println  Next item      s                                   catch  IOException e                    e printStackTrace                    This prints   Next item   Ljava lang String  6c8b058b Next item   Ljava lang String  1b192059 Next item   Ljava lang String  e9ac0f5 Next item   Ljava lang String  51f21c50 Next item   Ljava lang String  6e20f237 Next item   Ljava lang String  34fe315d Next item   Ljava lang String  1c5aebd9 Next item   Ljava lang String  1532021a Next item   Ljava lang String  62803d5 Next item   Ljava lang String  2d13981b Next item   Ljava lang String  61672bbb   I want to know if there is anyway I could access individual lines  elements via List   i e       1 2 3 4 5     6 7 8 9 10     11 12 13 14     15 16 17 18   I want String   nextLine   1 2 3 4 5  where nextLine 0    1 nextLine 1    2 etc   and in the next iteration nextLine should be 6 7 8 9 10 etc

User · Answer

String   is an array of Strings  Such an array is internally a class  Like all classes that don t explicitly extend some other class  it extends Object implicitly  The method toString   of class Object  by default  gives you the representation you see  the class name  followed by    followed by the hash code in hex  Since the String   class doesn t override the toString   method  you get that as a result   Create some method that outputs the array elements for you  Iterate over the array and use System out print    not print ln   on the elements

User · Answer

CSVReader reader   new CSVReader new FileReader                   myfile csv             try               List lt String   gt  myEntries   reader readAll                for  String   s   myEntries                   for String ss   s                       System out print        ss                                             catch  IOException e                e printStackTrace

User · Answer

Check out the split function of String Here  and use it something like this String   results   input split    s      The regular expresion bit spilts on whitespaces  it should do the trick

User · Answer

At this point   for  String   s   myEntries       System out println  Next item      s       You need to join the array of Strings in a line  Check this post  A method to reverse effect of java String split

User · Answer

The List interface supports random access via the get method - to get line 0  use list get 0    You ll need to use array access on that  ie  lines get 0  0  is the first element of the first line    See the javadoc here

User · Answer

The toString method of array types in Java isn t particularly meaningful  other than telling you what that is an array of   You can use java util Arrays toString for that   Or if your lines only contain numbers  and you want a line as 1 2 3 4    instead of  1  2  3        you can use   java util Arrays toString someArray  replaceAll

User · Answer

You have about 98  right  The only issue is that you re trying to print out an String   which does not print the way you d like  Instead try this     for  String   s   myEntries        System out print  Next item      s 0        for int i   1  i  lt  s length  i              System out print        s i              System out println          This way you re accessing each string in the array instead of the array itself   Hope this helps

[java] How to get to a particular element in a List in java?

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