Given two string variables a and b, swap these variables without using temporary or third variable in Java. Use of library methods is allowed.
Examples:
Input: a = "Hello"
b = "World"
Output:
Strings before swap: a = Hello and b = World
Strings after swap: a = World and b = Hello
The idea is to string concatenation and substring() method to perform this operation. The substring() method comes in two forms as listed below:
- substring(int beginindex): This fuction will return substring of the calling string starting from the index passed as argument to this function till the last character in the calling string.
- substring(int beginindex,int endindex): This function will return Substring of the calling string starting from the beginindex(inclusive) and ending at the endindex(exclusive) passed as argument to this function.
Algorithm:
1) Append second string to first string and
store in first string:
a = a + b
2) call the method substring(int beginindex, int endindex)
by passing beginindex as 0 and endindex as,
a.length() - b.length():
b = substring(0,a.length()-b.length());
3) call the method substring(int beginindex) by passing
b.length() as argument to store the value of initial
b string in a
a = substring(b.length());
// Java program to swap two strings without using a temporary // variable. import java.util.*; class Swap { public static void main(String args[]) { // Declare two strings String a = "Hello"; String b = "World"; // Print String before swapping System.out.println("Strings before swap: a = " + a + " and b = "+b); // append 2nd string to 1st a = a + b; // store intial string a in string b b = a.substring(0,a.length()-b.length()); // store initial string b in string a a = a.substring(b.length()); // print String after swapping System.out.println("Strings after swap: a = " + a + " and b = " + b); } } |
Output:
Strings before swap: a = Hello and b = World Strings after swap: a = World and b = Hello
References:
http://docs.oracle.com/
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