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Thread: How to reverse a string array ?

  1. #1
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    Default How to reverse a string array ?

    Hello again. I have an array of friends names and I want to print it in reverse. I know this question seems a bit lazy, but i really have tried casting the string as ints and even using lazy = String,valueOf(i) etc but No luck so far. Thanks

     
    //FriendList.java
     
    public class FriendList  {
     
      public static void main (String[] args)  {
     
      String [] friends = {"danny", "vic", "Laura", "Mike", "Jenny", "Asrath"};
     
      System.out.println ("My first 6 best friends are: ");
     
      for (String lazy : friends)
          System.out.println (lazy + " ");
     
      System.out.println ("Now them in reverse");
     
      //Problems begin here
     
      for (String lazy = friends.length; lazy >= 0; lazy--)
         System.out.println (lazy + " ");
     
      }
    }


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    Default Re: How to reverse a string array ?

    What should the reverse output look like? I'm not sure what you mean yet.

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    Default Re: How to reverse a string array ?

    The first for loop prints : Danny, vic , laura, mike , jenny, asrath.
    I want the second for loop to print them in reverse like: asrath, jenny mike, laura, vic. Danny.

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    Default Re: How to reverse a string array ?

    The first loop prints the array elements from 0 through 5. The second loop prints the array elements from 5 through 0. Try to code that.

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    Default Re: How to reverse a string array ?

    //FriendList.java
     
    public class FriendList  {
     
      public static void main (String[] args)  {
     
      String [] friends = {"danny", "vic", "Laura", "Mike", "Jenny", "Asrath"};
     
      System.out.println ("My first 6 best friends are: ");
     
      for (String lazy : friends)
          System.out.println (lazy + " ");
     
      System.out.println ("Now them in reverse");
     
      //Problems begin here
     
      System.out.println (friends[5]);
      System.out.println (friends[4]);
      System.out.println (friends[3]);
      System.out.println (friends[2]);
      System.out.println (friends[1]);
      System.out.println (friends[0]);
     
      }
    }
    I can't figure out how to do that I can only write them out manually. How do you move down through the array elements ?

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    Default Re: How to reverse a string array ?

    The enhanced for loop is a great tool, and I'm impressed that you're using it already, but unfortunately, it only iterates the collection in the forward direction. You'll have to write a loop, usually the standard for loop, to iterate the array in the reverse direction. Can you do that? Can you write a standard for loop in the forward direction? If so, start with that, and think about how you'd write it to go in the reverse direction. If you need help, show what you can do and ask for help.

  7. The Following User Says Thank You to GregBrannon For This Useful Post:

    craigjlner (November 9th, 2013)

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    Default Re: How to reverse a string array ?

    Well I did it Thanks Greg.
    //FriendList.java
     
    public class FriendList  {
     
      public static void main (String[] args)  {
     
      String [] friends = {"danny", "vic", "Laura", "Mike", "Jenny", "Asrath"};
     
      System.out.println ("My first 6 best friends are: ");
     
      for (int total = 0; total <= 5; total++)  {
          System.out.println (friends[total]);
      }
     
     
      System.out.println ("Now in reverse");
     
      for ( int total = 5; total >= 0; total--)  {
          System.out.println (friends[total]);
      }
      }
    }

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    Default Re: How to reverse a string array ?

    Good job! Glad to help, but I didn't do much.

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    Default Re: How to reverse a string array ?

    I'm impressed. There are many people new to programming that are unable to get the logic of printing stuff in reverse order. Going forward no probs. Going backwards nah too difficult.

    Well done!
    Improving the world one idiot at a time!

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    Default Re: How to reverse a string array ?

    What you are doing is going with a wrong for loop initialization. It will be like this:

    public class FriendList  {
     
      public static void main (String[] args)  {
     
      String [] friends = {"danny", "vic", "Laura", "Mike", "Jenny", "Asrath"};
     
      System.out.println ("My first 6 best friends are: ");
     
      for (String lazy : friends)
          System.out.print(lazy + " ");
     System.out.println();
      System.out.println ("Now them in reverse");
     
      //Problems begin here
     
      for (int lazy = (friends.length - 1); lazy >= 0; lazy--)
         System.out.print(friends[lazy] + " ");
     
      }
    }

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