CODEWITHSUNDEEP
java
user2504767
user2504767

Reputation:

How to concatenate a String in Java without using a complex code structure?

I have the following java code:

String strTest = null;

for (AlternativeEntity alternativeEntity : msg.Guidance()
      .getAlternatives()) {

    strTest = strTest + alternativeEntity.getArrivalStation().getName() + ", ";

}

The output looks like this:

nullabc, xyz, oop,

How can I solve this problem and very bad character format? It would be great if I can create output like this:

abc, xyz, oop

Upvotes: 0

Views: 144

Answers (9)

Amith
Amith

Reputation: 7008

Java provides StringBuilder class just for this purpose,its simple and easy to use.. 

    StringBuilder str = new StringBuilder("India ");

     //to append "Hi"
    str.append("Hi");

    // print the whole string
    System.out.println("The string is "+str)

the output will be : The string is India Hi

click here to know more about StringBuilder class

Upvotes: 1

Konstantin Yovkov
Konstantin Yovkov

Reputation: 62864

You can use Guava's Joiner#join(Iterable parts). For example:

Joiner joiner = Joiner.on(", ").skipNulls();
String result = joiner.join(list);
System.out.println(result);

Here, all the elements of the list will be printed comma separated without any trailing commas. Also, all the null elements will be skipped.

More info:

Upvotes: 3

Gene
Gene

Reputation: 46960

String strTest = null;

for (AlternativeEntity alternativeEntity : msg.Guidance().getAlternatives()) {
  String name = alternativeEntity.getArrivalStation().getName();
  strTest = (strTest == null) ? name : strTest +  ", " + name;
}

If the list is long, you should use a StringBuilder rather than the String for strTest because the code above builds a fresh string on each iteration: far too much copying.

Upvotes: 0

Masudul
Masudul

Reputation: 21961

Initialize strTest as:

String strTest = "";

Also, remove the last comma , 

strTest=strTest.substring(0, strTest.length()-1);

Upvotes: 3

Pranav Kale
Pranav Kale

Reputation: 639

Initialize String strTest="";

For skipping the last comma',' Use outside For loop:

strTest = strTest.substring(0,strTest.trim().length()-1);

Upvotes: 0

Evan Knowles
Evan Knowles

Reputation: 7501

Initialize your string to "":

 String strTest = "";

Alternatively, you should use a StringBuilder:

 StringBuilder builder = new StringBuilder();

 for (AlternativeEntity alternativeEntity : msg.Guidance()
  .getAlternatives()) {

     builder.append(alternativeEntity.getArrivalStation().getName()).append(", ");

 }

This will produce better performance.

Upvotes: 3

vishal_aim
vishal_aim

Reputation: 7854

why don't you use:

String strTest = "";

and at the end:

if(strTest.endsWith(", "))
   strTest = strTest.substring(0, strTest.length()-2);

Upvotes: 0

Juned Ahsan
Juned Ahsan

Reputation: 68715

Change

 String strTest = null;

to

String strTest = "";

Upvotes: 0

Julien
Julien

Reputation: 2584

Replace String strTest = null; by String strTest = "";

Upvotes: 0

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