Java Constructor isSynthetic()方法及示例

java.lang.reflect.Constructor类 的 isSynthetic() 方法是用来返回布尔值true，如果这个构造器对象是一个合成构造，则该方法返回false，显示该构造器不是一个合成构造。正如我们所知，合成构造是由Java编译器为内部目的而创建的类、字段和方法。在构造函数的例子中，合成构造是由java编译器为内部使用而创建的构造函数。这个方法有助于识别这些构造。

语法

public boolean isSynthetic()

参数： 此方法不接受任何参数。

返回 ：当且仅当这个可执行文件是《Java语言规范》所定义的合成结构时，该方法才会返回true。

下面的程序说明了isSynthetic()方法：

程序1 :

// Java program to illustrate isSynthetic() method
  
import java.lang.reflect.Constructor;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // create a class object
        Class classObj = shape.class;
  
        // get Constructor object
        // array from class object
        Constructor[] cons = classObj.getConstructors();
  
        // check isSynthetic or not
        boolean answer = cons[0].isSynthetic();
  
        // print result
        System.out.println("isSynthetic : " + answer);
    }
  
    @CustomAnnotation(createValues = "GFG")
    public class shape {
  
        @CustomAnnotation(createValues = "GFG")
        public shape()
        {
        }
    }
  
    // create a custom annotation
    public @interface CustomAnnotation {
        public String createValues();
    }
    }

输出:

isSynthetic : false

程序2

// Java program to illustrate isSynthetic() method
  
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // create a class object
        Class classObj = String.class;
  
        // get Constructor object
        // array from class object
        Constructor[] cons = classObj.getConstructors();
  
        for (int i = 0; i < cons.length; i++) {
  
            System.out.println("Constructor: "
                               + cons[i]);
  
            // get array of isSynthetic
            boolean answer = cons[0].isSynthetic();
  
            // print result
            System.out.println("isSynthetic : " + answer);
        }
    }
}

输出:

Constructor:  public java.lang.String(byte[], int, int)  
isSynthetic : false  
Constructor:  public java.lang.String(byte[], java.nio.charset.Charset)  
isSynthetic : false  
Constructor: public java.lang.String(byte[], java.lang.String) throws java.io.UnsupportedEncodingException  
isSynthetic : false  
Constructor: public java.lang.String(byte[], int, int, java.nio.charset.Charset)  
isSynthetic : false  
Constructor:  public java.lang.String(byte[], int, int, java.lang.String) throws java.io.unsupportedEncodingException  
isSynthetic : false  
Constructor: public java.lang.String(java.lang.StringBuilder)  
isSynthetic : false  
Constructor: public java.lang.String(java.lang.StringBuffer)  
isSynthetic : false  
Constructor: public java.lang.String(byte[])  
isSynthetic : false  
Constructor: public java.lang.String(int[], int, int)  
isSynthetic : false  
Constructor: public java.lang.String()  
isSynthetic : false  
Constructor: public java.lang.String(char[])  
isSynthetic : false  
Constructor: public java.lang.String(java.lang.String)  
isSynthetic : false  
Constructor: public java.lang.String(char[],int,in).String(char[], int, int)  
isSynthetic : false  
Constructor:  public java.lang.String(byte[], int)  
isSynthetic : false  
Constructor:  public java.lang.String(byte[], int, int, int)  
isSynthetic : false

参考资料: https://docs.oracle.com/javase/10/docs/api/java/lang/reflect/Constructor.html#isSynthetic()