Java Compare Strings

Question

 /**
 * A method to compare Strings
 * @param arg1
 * @param arg2
 * @return 
 */
public boolean myQuickCompare(String arg1, String arg2) {
    boolean a = arg1.length() == arg2.length();
    if (a) {
        for (int b = 0; b > arg1.length(); b++) {
            if (arg1.charAt(b) != arg2.charAt(b)) {
                a = false;
            }
        }
    }
    return a;
}

I understand that the for loop is the wrong way around, b will never be greater than the length of the string. How would you correct this problem?

What sensible variable names would you give for a and b?

*Why* do you ask this? Do you really want to replace `String.equals()` or are you just implement this for learning? — Joachim Sauer, Jul 18 '11 at 09:56

score 6 · Answer 1 · answered Jul 18 '11 at 09:30

6

Use arg1.equals(arg2). No need for custom functions. Don't try to outsmart the developers of Java. Most of the time, they win.

answered Jul 18 '11 at 09:30

Jacob

41,721
6
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score 2 · Answer 2 · edited Jun 20 '20 at 09:12

I understand that the for loop is the wrong way around, b will never be greater than the >length of the string. How would you correct this problem?

use `equals()` of `String` directly

What sensible variable names would you give for a and b?

a may be result

b may be index

Here is the implementation of equals() from open jdk 7

 public boolean equals(Object anObject) {
 1014           if (this == anObject) {
 1015               return true;
 1016           }
 1017           if (anObject instanceof String) {
 1018               String anotherString = (String)anObject;
 1019               int n = count;
 1020               if (n == anotherString.count) {
 1021                   char v1[] = value;
 1022                   char v2[] = anotherString.value;
 1023                   int i = offset;
 1024                   int j = anotherString.offset;
 1025                   while (n-- != 0) {
 1026                       if (v1[i++] != v2[j++])
 1027                           return false;
 1028                   }
 1029                   return true;
 1030               }
 1031           }
 1032           return false;
 1033       }

score 2 · Answer 3 · answered Jul 18 '11 at 09:34

2

I always use StringUtils.compare ( Apache Commons ). This handles the null case for either String argument as well.

answered Jul 18 '11 at 09:34

ivy

5,539
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score 0 · Answer 4 · answered Jul 18 '11 at 09:31

0

a => result b => current

It would be helpful to check if either of arguments is null.

answered Jul 18 '11 at 09:31

Boris Pavlović

63,078
28
122
148

1

I wouldn't use `current`, as that could be mistaken as "the current character" while it's "the current index". `index` is probably better. – Joachim Sauer Jul 18 '11 at 09:55

score 0 · Answer 5 · answered Jul 18 '11 at 09:33

A couple of things:

When you compare strings for equality, use the .equals method. == is used to compare object references and see if they refer to the same instance. .equals actually compares the characters inside the String object.
Even if you do things your way (which is incorrect), the for loop should look like this

for (int b = 0; b < arg1.length(); b++)

Java Compare Strings

5 Answers5

use `equals()` of `String` directly

Linked

Java Compare Strings

5 Answers5

use equals() of String directly

Linked

use `equals()` of `String` directly