CODEWITHSUNDEEP
javastringstringbuffer
Santino 'Sonny' Corleone
Santino 'Sonny' Corleone

Reputation: 1753

Append a int variable to a StringBuffer

I have this code

String str1 = (String) optionlist1.get(i);//str1=apple
String str2 = (String) optionlist2.get(i);//str2=mango
String str3 = (String) optionlist3.get(i);//str3=water

for(int k=1;k<4;k++){
   String str="str"+k;
   sb.append("<p>"+k+")"+str+"</p>");
}

When I print this I just get str1,str2,str3 instead of the actual data i.e apple,mango,water.

Is there a way to do this ? Let me know if more info is required.

Upvotes: 0

Views: 881

Answers (5)

npinti
npinti

Reputation: 52185

That will not work since you are stating that str = "str" + k, which means that str will have values of str1, str2, etc. These values represent string literals, and not variable names. To go round your problem you can do this:

List<String> fruit = new ArrayList<String>();
fruit.add((String) optionlist1.get(i));
fruit.add((String) optionlist2.get(i));
fruit.add((String) optionlist3.get(i));

for(String str : fruit)
{
    System.out.println(str);
}

What you are trying to achieve is possible through the Reflection API (more on that here), however I think that for your particular problem, using reflection might be a little bit overkill, so it might be better to stick with the easier solutions.

EDIT: This code should do what you are after through the use of reflection:

    public static List<String> lst0 = new ArrayList<String>();
    public static List<String> lst1 = new ArrayList<String>();

    public static void main(String[] args) throws NoSuchElementException, NoSuchFieldException, IllegalAccessException
    {

       lst0.add("abc");       
       lst1.add("def");

       Class thisClass = SOTest.class;
       for(int i = 0; i < 2; i++)
       {
           Field field = thisClass.getField("lst" + i);
           List<String> lst = (List<String>) field.get(new ArrayList<String>());
           System.out.println(lst.get(0));
       }
    }

Upvotes: 2

SaurabhJinturkar
SaurabhJinturkar

Reputation: 554

str1, str2 and str3 are variable names. You are creating variable names as a String str = "str" + k which is ultimately a value not variable name.

You need to create an array of String to store your options.

String[] strs = new String[];

You can add your str1, str2.. to this array.

strs[0] = str1; strs[1] = str2; strs[2] = str3;

and access this array in your for loop. 

for(int k=0; k < 3; k++) { 
    String str="str"+k;
    sb.append("<p>"+ strs[k] + "</p>");
}

This will work. :)

Upvotes: 1

Suresh Atta
Suresh Atta

Reputation: 121998

Variable names cannot generate Dynamically.

You could try,

List<String> list = new ArrayList<String>();
list.add((String) optionlist1.get(i));//str1=apple
list.add((String) optionlist2.get(i));//str2=mango
list.add((String) optionlist3.get(i));//str3=water

int counter=1;
for(String str : list){
sb.append("<p>"+counter+")"+str+"</p>");
counter++;
}

Upvotes: 1

Scary Wombat
Scary Wombat

Reputation: 44824

A String by the name of str1 is not the same as a String with the value of str1

e.g.

  String str1 = "Apple";

  str1.equals ("str1") == false;

try using an array

String str[] = new String [3];
str[0] = (String) optionlist1.get(i);//str1=apple
str[1] = (String) optionlist2.get(i);//str2=mango
str[2] = (String) optionlist3.get(i);//str3=water

and then

for(int k=1;k<4;k++){
    String s=str[k-1];
    sb.append("<p>"+k+")"+s+"</p>");
}

Upvotes: 1

Juned Ahsan
Juned Ahsan

Reputation: 68715

you cannot reference variables using their string literal because string "str1" is not equal to reference variable str1. One alternate approach can be to use an array as mentioned here:

    String strArrr[] = new String[3];

    String strArrr[0] = (String) optionlist1.get(i);//str1=apple
    String strArrr[1] = (String) optionlist2.get(i);//str2=mango
    String strArrr[2] = (String) optionlist3.get(i);//str3=water


    for(int k=1;k<4;k++){
    String str=strArr[k-1];
    sb.append("<p>"+k+")"+str+"</p>");
    }

Upvotes: 1

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