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Java Program to swap two string variables without using third or temp variable.

In this program, we need to swap two strings without using a third variable.

Str1: Good Str2: morning

Swapping two strings usually take a temporary third variable. One of the approach to accomplish this is to concatenate given two strings into first string.

Str1Str1 = Str1 + Str2= Goodmorning

Extract string 2 using substring (0, length(string1) - (string2)) i.e. in our case it will be substring(0, (11-4)). It will assign string Good to string 2 which is highlighted by green.

Str2 = Goodmorning

Extract string 1 using substring (length(string2)) i.e. we need to extract string from in length(string2) till end of the string. In our case it will be substring(4). It will assign string morning to string 1 which is highlighted by green.

Str1 = Goodmorning


  • STEP 2: DEFINE Strings str1 = "Good ", str2 = "morning " to swap
  • STEP 3: PRINT "Strings before swapping " str1, str2
  • STEP 4: str1 =str1 + str2
  • STEP 5: EXTRACT str1 from indexes 0 to length (str1) - (str2) using substring function and store it in str2.
  • STEP 6: EXTRACT str1 from index length(str2) till end using substring function and store it in str1.
  • STEP 7: PRINT "Strings after swapping " str1, str2.
  • STEP 8: END



Strings before swapping: Good morning
Strings after swapping: morning Good
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