Issue with the "if" statement

Question

I'm taking a CS course and this code is giving me problems.

         while (statScan.hasNext()){

        currentStat = statScan.next();
        if (currentStat =  h);
        {       
            hStat++;
        }
        System.out.println("" + currentStat);

Look at the "if" statement. Java says "cannot convert string to boolean" and from my understanding boolean is a true/false sorta thing so what Java isn't understanding is how to evaluate and compare the strings. How do I force it to do so?

Goran Štuc · Answer 1 · 2012-12-02T01:37:31.770

4

the problem is that you assign it instead of ask if it's equal (assign '=', equals '==')
this is the solution for that line: also if it's strings use .equals()

if (currentStat.equals(h))

edited Dec 02 '12 at 01:37

answered Dec 02 '12 at 01:28

Goran Štuc

581
4
15

1

don't use == on objects. use .equals instead. – ApproachingDarknessFish Dec 02 '12 at 01:29
it's in the comment, i said if that is a string(which it is) that he should use equals – Goran Štuc Dec 02 '12 at 01:30
@GoranŠtuc It is preferable to you to edit the question and put the equals instead – dreamcrash Dec 02 '12 at 01:35
there, also a word of advice if you use the if statement to avoid such errors in the future if it's against a constant what i do is for example: DialogResult dr = someform.showdialog(); if(DialogResult.Ok == dr){} – Goran Štuc Dec 02 '12 at 01:39

score 1 · Accepted Answer · edited May 23 '17 at 10:24

The = operator in Java is intended as an assignment operator, so when you write x = y you don't mean is x equal to y but assign value of y to x.

The comparison operator is the == operator but this will compare either primitive types (int, char, float, etc) either references to objects that is not the usual behavior you need. For anything that is not a primitive type you should consider using the method inherited by Object which is boolean equals(Object o). To understand exactly why it is so, take a look here or here.

score 1 · Answer 3 · answered Dec 02 '12 at 01:32

A few problems here:

if (currentStat =  h);

First, you have a semicolon at the end which will cause the if-statement to not function as you want. It is basically conditionally executing an empty statement. The following block of code (which you intended to be conditional) will always be run. Remove the semicolon to avoid this.

Also, you only have = instead of ==. This means you are assigning the value of h to currentStat. This is a classic, classic typo. As @YogendraSingh mentioned in the other answer, you should use the equals() method to perform comparisons on strings in Java. Otherwise you are only comparing to see if the two items are exactly the same object. Do detect when the same string text is held in two different objects you need to use equals().

So change this line to:

if (h.equals(currentStat))

Kudos for picking up the stray semicolon. – clstrfsck Dec 02 '12 at 01:43 — clstrfsck, Dec 02 '12 at 01:43

score 0 · Answer 4 · answered Dec 02 '12 at 01:26

0

Assuming h is a string, use equals method for string comparison as:

      if(currentStat.equals(h))

Currently you are using assignment operator =, which assigns the string value of h to currentStat.

When you change the operator to comparison operator == then it will compare the object instance equality and not the value, which I think you don't want/

answered Dec 02 '12 at 01:26

Yogendra Singh

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6
63
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@user1869638: I am really surprised this time with the suggestions of using `==` operator to compare the string and that also getting voted so much :) I have never seen this before. May be, I am missing something big here. Since you are using `scan.next()`, I know its string and hence I advice you to use `equals` not `==`. – Yogendra Singh Dec 02 '12 at 01:31

Issue with the "if" statement

4 Answers4