Java 5 Annotation-优快云博客

本文介绍了如何使用Java注解来标记需要完成的任务，并通过实例展示了不同类型的注解应用，包括简单的标记注解和带有成员变量的复合注解。

@Interface is similar to Interface just it is used as templates for documentation, as a standard; especially useful for team development. However, it's pain on the butt - making the coding so difficult to read.

Example 1:

@interface - declaration

package com.myannotation.examples;

/**
 * Marker annotation to indicate that a method or class
 *   is still in progress.
 */
public @interface InProgress { }

@interface - using

@com.myannotation.examples.InProgress
public void calculateInterest(float amount, float rate) {
  // Need to finish this method later
}

@interface - add a member

package com.myannotation.examples;

/**
 * Annotation type to indicate a task still needs to be
 *   completed.
 */
public @interface TODO {
  String value();
}

@interface - using with a member

@com.myannotation.examples.InProgress
@TODO("Need to figure out my debt")
public void calculateMyDebt(float amount, float rate) {
// Need to finish this method later
}

@com.myannotation.examples.InProgress
@TODO(value="Need to figure out my debt")
public void calculateMyDebt(float amount, float rate) {
// Need to finish this method later
}

Example 2: A little bit complicate case

package com.myannotation.examples;

public @interface GroupTODO {

  public enum Severity { CRITICAL, IMPORTANT, TRIVIAL, DOCUMENTATION };

  Severity severity() default Severity.IMPORTANT;
  String item();
  String assignedTo();
  String dateAssigned();
}
@com.myannotation.examples.InProgress
@GroupTODO(
    item="Need to figure out my debt",
    assignedTo="chefZ",
    dateAssigned="08/04/2007"
)

public  void calculateMyDebt(float amount, float rate) {
    // Need to finish this method later
}

@com.myannotation.examples.InProgress
@GroupTODO(
    severity=GroupTODO.Severity.DOCUMENTATION,
    item="Need to explain why I have to pay",
    assignedTo="chefZ",
    dateAssigned="08/04/2008"
)

public  void reallyConfusedPayment(int codePoint) {
    // Really weird payment  }

If someone expect me to enjoy coding this, he must have some nerds. :-) However, more to come.