類的成員包含變數（Field）,方法（Method），構造器（Constructor）

類定義

package Reflect;

public class MyTest {
    public int a;
    public static int b;
    public static final int c = 0;
    private int d;

    public int sum(int a, int b, String c) {
        return a + b;
    }

    public int sub(int a, int b, String c) {
        
 
return a - b;
    }

    MyTest() {

    }

    MyTest(int a, int b) {

    }
}

1.獲取變數

package Reflect;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

public class Test {
    public static void
 
 main(String[] args) {
        System.out.println(MyTest.class);
        final Class<?> clazz = MyTest.class;
        System.out.println(clazz.getClass());
        final Field[] fields = clazz.getDeclaredFields();

        System.out.println("====print fields===");
        for (final Field f : fields) {
            System.out.print(f.getName() 
 
+ "->");
            System.out.print(f.getModifiers() + "->");
            System.out.println(Modifier.toString(f.getModifiers()));
        }


}
輸出：
class Reflect.MyTest
class java.lang.Class
====print fields===
a->1->public
b->9->public static
c->25->public static final
d->2->private

2.獲取方法

package Reflect;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;


public class Test {
    public static void main(String[] args) {
        System.out.println(MyTest.class);
        final Class<?> clazz = MyTest.class;
        System.out.println(clazz.getClass());
        final Field[] fields = clazz.getDeclaredFields();

        System.out.println("====print Method===");
        final Method[] ms = clazz.getMethods();
        for (final Method m : ms) {
            System.out.println();
            System.out.print(m.getName() + "==||");
            System.out.print(m.getReturnType().getName() + "==||");
            for (final Class o : m.getParameterTypes()) {
                System.out.print(",==" + o.getName());
            }
        }
    
    }
}
輸出:
====print Method===
sum==||int==||,==int,==int,==java.lang.String
sub==||int==||,==int,==int,==java.lang.String
wait==||void==||
wait==||void==||,==long,==int
wait==||void==||,==long
hashCode==||int==||
getClass==||java.lang.Class==||
equals==||boolean==||,==java.lang.Object
toString==||java.lang.String==||
notify==||void==||
notifyAll==||void==||

3.獲取構造器

package Reflect;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;


public class Test {
    public static void main(String[] args) {
        System.out.println(MyTest.class);
        final Class<?> clazz = MyTest.class;
        System.out.println(clazz.getClass());

        System.out.println();
        System.out.println("====print Constructor===");
        final Constructor[] cs = clazz.getDeclaredConstructors();
        for (final Constructor c : cs) {
            System.out.println();
            System.out.print(c.getName());
            for (final Class o : c.getParameterTypes()) {
                System.out.print(",==" + o.getName());
            }
        }

    }
}

輸出：
====print Constructor===
Reflect.MyTest 
Reflect.MyTest,==int,==int