java.lang.NullPointerException [duplicate]

This question already has answers here: What is a NullPointerException, and how do I fix it? (12 answers) Closed 7 years ago.

I keep getting this exception:

Exception in thread "Thread-1" java.lang.NullPointerException
        at Info.<init>(Info.java:168)
        at Rcon.data(Rcon.java:130)
        at Rcon$1.run(Rcon.java:105)

Line 168 is at bot.redScore = Integer.parseInt(matcher.group(2));

    else if(str.indexOf("current score") != -1) {
        pattern = "Team \\\"(\\w+)\\\" current score \\\"(\\d+)\\\"";
        p = Pattern.compile(pattern);
        matcher = p.matcher(str);
        if(matcher.find()) {
            if(matcher.group(1).equalsIgnoreCase("Red")) {
                bot.redScore = Integer.parseInt(matcher.group(2));

            }
            else if(matcher.group(1).equalsIgnoreCase("Blue")) {
                bot.blueScore = Integer.parseInt(matcher.group(2));
            }
            cmd = "score";
        }
    }

I have no clue开发者_运维技巧 why I keep getting this error. The str that is being parsed using regex is:

Processing: Team "Red" current score "1" with "1" players

When I am running only this part by itself, it works fine. But when I am running the whole program I get this exception.

bot.blueScore and bot.redScore are being declared in another class as follows:

int redScore = 0;
int blueScore = 0;

Also I have checked the contents of matcher.group(2), and it returns an integer, anywhere from 0 to 10. Any ideas? I have been struggling with this for hours now.

Thanks!

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bot is likely to be null. Make sure it is not null (initialize it)

That said, you should learn to read exceptions - this is a very core skill. NullPointerException is the most common exception - you already identified the line, and if you check the documentation of the exception, you will see that it usually occurs when a reference is null and you are trying to access methods/fields on it.

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If you get a null pointer exception look for expressions on the line of the form x.y and ask yourself why x is null. In your case either bot or matcher must be null. Since you got into that line using matcher on the previous line, your variable bot is null.