The performance optimization skills of the Invariant framework in the Java library
The performance optimization skills of the Invariant framework in the Java library
introduction:
In Java development, performance optimization is a very important topic.With the expansion of the scale of the application and the increase of function, we often need to optimize performance to improve the response speed and efficiency of the application.In the Java class library, using the Invariant framework is an effective performance optimization technique.This article will introduce the concepts of constant framework and provide some techniques and example code that uses constant frameworks in the Java class library for performance optimization.
1. The concept of Invariant framework:
The constant framework is a design pattern. By ensuring that the state of the object does not change after creation, it provides more efficient code execution.The state of the unchanged object is fixed after creation, so they do not need to perform synchronization or copy operations to avoid some performance overhead.In Java, the constant framework can be achieved through the following steps:
-All fields are set to private and final to ensure that they cannot be modified.
-Colin the public method without any modification fields.
-If the state of the class can be modified from the outside, then returns a new non -changing object instead of modifying the existing object.
2. The performance optimization technique of constant framework:
Here are some techniques to optimize performance in the Java class library for performance optimization:
2.1 Unchanged collection:
Java provides a series of collection classes, such as ArrayList and HashMap.However, these collection classes may have thread security issues in multi -threaded environments.To solve this problem, we can use the unchanged collection class, such as Collections.unmodifiableList and Collections.unmodifiablemapmap.These non -changing collection classes cannot be modified after the creation, so it can ensure the safety of the thread and do not need to be synchronized when sharing between multiple threads.
Java code sample: use unchanged collection
List<String> list = new ArrayList<>();
// Add element to list
list.add ("Element 1");
list.add ("Element 2");
list.add ("Element 3");
List<String> unmodifiableList = Collections.unmodifiableList(list);
// Try to modify the unchanged collection
unmodifiableList.add ("New Element"); // Throw out unsupportedOperationException
2.2 Cache unchanged object:
In some cases, the cost of creating objects may be high.In order to improve performance, we can use the cache mechanism to reuse the unchanged object.For example, assuming we need to use a specific string object in the code frequently, we can create the string object as the same object and cache it so that the cache object that is cached directly, not the object of the cache instead of it, notCreate a new object every time.
Java code sample: cache does not change object
class StringCache {
private static final Map<Integer, String> cache = new HashMap<>();
public static String getImmutableString(int key) {
if (cache.containsKey(key)) {
return cache.get(key);
} else {
String newString = createImmutableString(key);
cache.put(key, newString);
return newString;
}
}
private static String createImmutableString(int key) {
// Create the logic of constant string
Return "constant string" + key;
}
}
2.3 Use Ninxin Object as a key for MAP:
When using MAP, the implementation of the HashCode () and Equals () methods of the keys is essential for performance.In order to improve performance, we can use the results of constant objects as MAP, because the results of the HashCode () and Equals () methods of unchanged objects will not change, and cache can be used to improve efficiency.
Java code example: use the key of the unchanged object as the key of the MAP
class ImmutableKey {
private final int value;
public ImmutableKey(int value) {
this.value = value;
}
@Override
public int hashCode() {
// Calculate HashCode for the unchanged fields
return Objects.hashCode(value);
}
@Override
public boolean equals(Object obj) {
// Compare EQUALS for non -changing fields
if (this == obj) return true;
if (obj == null || getClass() != obj.getClass()) return false;
ImmutableKey other = (ImmutableKey) obj;
return value == other.value;
}
}
// Use unchanged objects as a key for MAP
Map<ImmutableKey, String> map = new HashMap<>();
ImmutableKey key = new ImmutableKey(42);
map.put (key, "value");
String value = map.get(key);
System.out.println (value); // Output: value
in conclusion:
Using the constant framework is an effective performance optimization technique that can improve the code execution efficiency in the Java class library.By using unchanged collection, cache constant objects, and use of unchanged objects as MAP keys, we can avoid some performance overhead and improve the performance of the application.In Java development, we should choose appropriate performance optimization skills based on specific circumstances and perform performance optimization on the premise of ensuring the readability and maintenance of the code.
