Re-Assaigning a string variable to StringBuffer Object

Question

This is a block of code in one of my program. if i directly assign sb1= str2 i am getting an error. so i am creating two StringBuffer objects.

Is there any possibility to achieve below requirement using only one StringBuffer Object.

   String str1, str2;
    Scanner scanObj = new Scanner(System.in);
    str1 = scanObj.next();
    StringBuffer sb1 = new StringBuffer(str1);
    sb1.reverse();
    str1 = sb1.toString();
    char[] input1 = str1.toCharArray();
    str2 = scanObj.next();
    StringBuffer sb2 = new StringBuffer(str2);
    sb2.reverse();
    str2 = sb2.toString();
    char[] input2 = str2.toCharArray();

Unless you need thread safety, you should use StringBuilder. It was introduced in Java 5 in 2004 and is preferred to StringBuffer. — Peter Lawrey
– Peter Lawrey, Commented Jun 14, 2012 at 11:45

Thom · Accepted Answer · 2012-06-14 11:53:39Z

1

use sb.setLength(0) and then add the new string back in. This should keep the same memory allocation.

answered Jun 14, 2012 at 11:53

Thom

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Peter Lawrey · Accepted Answer · 2012-06-14 11:52:50Z

0

You can write

Scanner scanObj = new Scanner(System.in);
char[] input1 = new StringBuilder(scanObj.next()).reverse().toString().toCharArray();
char[] input2 = new StringBuilder(scanObj.next()).reverse().toString().toCharArray();

You can reuse a StringBuilder by using setLength(0) and append() but it would be more complex.

answered Jun 14, 2012 at 11:52

Peter Lawrey

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2 Comments

Thom Over a year ago

More complex how? Your approach could cause the memory to be re-allocated.

Peter Lawrey Over a year ago

@Thom if you were worries about memory allocations you would just use a loop over a char[] and not have any StringBuilder. Given the program is not likely to worry about anything less than a micro-second, code simplicty is more likely to be important.

Paulius Matulionis · Accepted Answer · 2012-06-14 11:53:13Z

0

You can not assign StringBuffer directly to String because there are different objects. This should help you:

String yourStr = "some value";
StringBuffer buffer = new String(yourStr);
StringBuffer other = buffer;

You can put any String value into the StringBuffer object constructor.

answered Jun 14, 2012 at 11:53

Paulius Matulionis

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