Java Method類 isDefault()用法及代碼示例

java.lang.reflect.Method.isDefault()方法用於檢查Method對象的方法是否為Default Method ：。如果方法對象是默認方法，則返回true，否則將返回false。

默認方法：公共非抽象on-static方法，其主體以接口類型聲明。

用法:

public boolean isDefault()

返回值：此方法返回一個布爾值。如果方法對象是JVM規範的默認方法，則返回true，否則返回false。

以下示例程序旨在說明Method類的isDefault()方法：

範例1：

/* 
* Program Demonstrate isDefault() method  
* of Method Class. 
*/
import java.lang.reflect.Method; 
public class GFG { 
  
    // create main method 
    public static void main(String args[]) 
    { 
  
        try { 
  
            // create class object for interface Shape 
            Class c = Shape.class; 
  
            // get list of Method object 
            Method[] methods = c.getMethods(); 
  
            // print Default Methods 
            for (Method m:methods) { 
  
                // check whether the method is Default Method or not 
                if (m.isDefault()) 
                    // Print 
                    System.out.println("Method:"
                                       + m.getName() 
                                       + " is Default Method"); 
            } 
        } 
        catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
  
    private interface Shape { 
    default int
        draw() 
        { 
            return 0; 
        } 
  
        void paint(); 
    } 
}

輸出：

Method:draw is Default Method

範例2：

/* 
* Program Demonstrate isDefault() method  
* of Method Class. 
* This program checks all default method in Comparator interface 
*/
import java.lang.reflect.Method; 
import java.util.Comparator; 
public class Main6 { 
  
    // create main method 
    public static void main(String args[]) 
    { 
  
        try { 
  
            // create class object for Interface Comparator 
            Class c = Comparator.class; 
  
            // get list of Method object 
            Method[] methods = c.getMethods(); 
  
            System.out.println("Default Methods of Comparator Interface"); 
            for (Method method:methods) { 
                // check whether method is Default Method or not 
                if (method.isDefault()) 
                    // print Method name 
                    System.out.println(method.getName()); 
            } 
        } 
        catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
}

輸出：

Default Methods of Comparator Interface
reversed
thenComparing
thenComparing
thenComparing
thenComparingInt
thenComparingLong
thenComparingDouble

參考：
https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#isDefault-

相關用法

注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 Method Class | isDefault() Method in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。