1.string invariance
Here's a picture showing what this code does
12 |
String s = "abcd" ; s = s.concat( "ef" ); |
2.the difference between the Equals () method, the Hashcode () method
Hashcode is designed to improve performance. The difference between the Equals () method and the Hashcode () method is that:
- If two objects are equal (equal), then they must have the same hash value.
- If two objects have the same hash value, they may not be equal (equal).
3.Hierarchy of Java exception classes
The red part of the figure is checked for exceptions. They must be caught, or declared in the function to throw the exception.
4.Hierarchy of collection classes
Notice the difference between collections and collection. (collections contains a variety of static polymorphism methods for set operations)
5.Java Synchronization
The Java synchronization mechanism can be illustrated by analogy to buildings.
6.aliases
An alias means that there are multiple variables pointing to the same block of memory that can be updated, respectively, with different object types.
7.Heap and Stack
The plot shows the location of the method and the object in memory at run time.
8.Java Virtual runtime data region
The illustration shows the situation of the data region when the entire virtual runtime is running.
This paper draws on http://www.importnew.com/11725.html
Crazy Java Learning notes----------8 diagrams to understand Java