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    <p><code>null</code> assignments do not change <em>value</em> by globally destroying that object. That kind of behavior would lead to hard-to-track bugs and counterintuitive behavior. They only break that specific <em>reference</em>.</p> <p>For simplicity, let's say that <code>sample</code> points to address 12345. This is probably not the address, and is only used to make things simple here. <strike>The address is <em>typically</em> represented with the weird hexadecimal given in <code>Object#hashCode()</code>, but this is implementation-dependent.</strike><sup>1</sup></p> <pre><code>StringBuilder sample = new StringBuilder(); //sample refers to //StringBuilder at 12345 StringBuilder referToSample = sample; //referToSample refers to //the same StringBuilder at 12345 //SEE DIAGRAM 1 referToSample = null; //referToSample NOW refers to 00000, //so accessing it will throw a NPE. //The other reference is not affected. //SEE DIAGRAM 2 sample.append("A"); //sample STILL refers to the same StringBuilder at 12345 System.out.println(sample); </code></pre> <p><em>From the lines marked <code>See diagram</code> the diagrams of the objects at that time are as follows:</em></p> <p><strong>Diagram 1:</strong></p> <pre><code>[StringBuilder sample] -----------------&gt; [java.lang.StringBuilder@00012345] ↑ [StringBuilder referToSample] ------------------------/ </code></pre> <p><strong>Diagram 2:</strong></p> <pre><code>[StringBuilder sample] -----------------&gt; [java.lang.StringBuilder@00012345] [StringBuilder referToSample] ----&gt;&gt; [null pointer] </code></pre> <p>Diagram 2 shows that annulling <code>referToSample</code> does not break the reference of <code>sample</code> to the StringBuilder at <code>00012345</code>.</p> <p><sub><sup>1</sup>GC considerations make this implausible.</sub></p>
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    1. POWhy is this not throwing a NullPointerException?
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    1. USgsamaras
    1. USAndrey Akhmetov
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    1. POWhy is this not throwing a NullPointerException?
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    1. CO@commit, if this answers your question, please click the tick below the vote arrows to the left of the text above.
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      1. USRay Britton
    2. CO@RayBritton I love how people assume that the highest voted answer is the one that necesarily answers the question. While that count is important it is not the only metric; -1 and -2 answers can get accepted just because they helped the OP the most.
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      1. USAndrey Akhmetov
    3. CO@hexafraction I thought `null` is a value so if I assign to one it should also assign to other but as simple example given by you I got clear and just for I want to know that if I assign any object with `null` it will refer to `00000` kind of address or is just an example?
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