8 pictures take you to understand Java, can you do it?

A picture is worth a thousand words. If the diagram does not clarify the problem, you can use its title to get a glimpse.

String immutability

The picture below shows what this code does

String s = "abcd";
s = s.concat("ef");

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The difference between equals() method and hashCode() method

HashCode is designed to improve performance. The difference between equals() method and hashCode() method is:

If two objects are equal, then they must have the same hash value.

If the hash values of two objects are the same, they may not be equal.
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The hierarchy of Java exception classes

The red part in the picture is the abnormality under inspection. They must be caught, or declared in the function to throw the exception.
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The hierarchy of collection classes

Note the difference between Collections and Collection. (Collections contains a variety of static polymorphic methods related to collection operations)
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Java synchronization

The Java synchronization mechanism can be illustrated by analogy buildings.

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Alias

Alias means that there are multiple variables pointing to the same memory block that can be updated, and these aliases are of different object types.
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Heap and stack

The diagram shows the location of methods and objects in runtime memory.
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Java virtual machine runtime data area

The diagram shows the data area when the entire virtual machine is running.
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At last

Here, Timo also compiled some technical documents that he usually learned and interview materials that his group friends usually interview.
If it helps you after reading it, remember to like it and support it!

Ps: Those in need can click to enter the secret code: csdn , and get it for free.

Interview topic documents.

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Technical documents

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Real big factory experience

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