Unreachable variable within while loop?

Question

Why is my variable non reachable within the following loop method (i++ is not reachable)?

    public String returnFailedImages() {
    int i = 0;
    while(i < failedScreenshotImages.size()) {
        return "<img src='" + failedScreenshotImages.get(i) + "'" + ">" + "</br>";
        i++;
    }
    return null;
}

Also if i use a for loop (i++ is not being used)?:

    public String returnFailedImages() {
    for(int i = 0;i < failedScreenshotImages.size(); i++) {
        return "<img src='" + failedScreenshotImages.get(i) + "'" + ">" + "</br>";
    }
    return null;
}

`i++` is unreachable because you return the value before that statement. — Sanket Makani, May 08 '17 at 13:54
Possible duplicate of [Unreachable code: error or warning?](http://stackoverflow.com/questions/2280787/unreachable-code-error-or-warning) — freedev, May 08 '17 at 13:57

score 5 · Accepted Answer · answered May 08 '17 at 13:57

Based on the name of your method, you want to return multiple elements. You could either return a List<String> or concatenate all the Strings of the failed images :

public String returnFailedImages() {
    StringBuilder result = new StringBuilder();
    for(int i = 0;i < failedScreenshotImages.size(); i++) {
        result.append("<img src='" + failedScreenshotImages.get(i) + "'" + ">" + "</br>");
    }
    return result.toString();
}

score 1 · Answer 2 · answered May 08 '17 at 14:00

When you do this:

while(i < failedScreenshotImages.size()) {
        return "<img src='" + failedScreenshotImages.get(i) + "'" + ">" + "</br>";
        i++;
}

You are actually ending your method in the return statement, therefore you'll never reach the i++ statement. You should do as follows:

public String[] returnFailedImages() {
  int i = 0;
  String[] res = new String[failedScreenshotImages.size()];
  while(i < failedScreenshotImages.size()) {
      res[i] = "<img src='" + failedScreenshotImages.get(i) + "'" + ">" + "</br>";
      i++;
  }
  return res;
}

Then you can just iterate through the array to get your images.

score 0 · Answer 3 · answered May 08 '17 at 13:55

0

because your return statemant is before the line i++;.

answered May 08 '17 at 13:55

SF23

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score 0 · Answer 4 · answered May 08 '17 at 13:55

0

You are returning from your method before you reach the line with i++. I suspect you want to build a result before which you extend for every different i, so that you can return this construct at the end.

answered May 08 '17 at 13:55

C-Otto

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thanks for the message could you add the code that you would use please? – Gbru May 08 '17 at 13:58
Have a look at Eran's answer. – C-Otto May 08 '17 at 14:00

score 0 · Answer 5 · answered May 08 '17 at 14:05

0

A return statement hands over the control to the function it is called from and can place some value / object to the stack. (The return value.)

In your code you place a String (

answered May 08 '17 at 14:05

Gerard de Jong

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Unreachable variable within while loop?

5 Answers5