1 class Test1{
 2     static{
 3         System.out.println("loading1");
 4     }
 5
 6 }
 7 class Test2{
 8     static{
 9         System.out.println("loading2");
10     }
11
12 }
13 class Test3{
14     static{
15         System.out.println("loading3");
16     }
17
18 }
19 public class Demo {
20     public static void main(String[] args) {
21         //new Test1();
22         Class clz = Test1.class;//注意Class clz = Test1.class;，不会触发静态块的执行，即不会自动初始化该Class对象
23         try {
24
25             Class.forName("Test2");
26         } catch (ClassNotFoundException e) {
27             e.printStackTrace();
28         }
29         new Test3();
30     }
31
32 }

loading1
loading2
loading3

 1 /**
 2 *    获取Class对象的三种方式
 3 */
 4 public class Demo{
 5     public static void main(String[] args){
 6         //1.通过实例对象获取class对象
 7         Demo demo = new Demo();
 8         Class clsdemo = demo.getClass();
 9
10         //2.通过Class的静态方法forName
11         try {
12             Class clsdemo2 = Class.forName("Demo");
13         } catch (ClassNotFoundException e) {
14             e.printStackTrace();
15         }
16
17         //3.通过类名和class关键字获取
18         Class clsdemo3 = Demo.class;
19     }
20 }

 1 public class Demo{
 2     public static void main(String[] args){
 3
 4         Test test = new Test();
 5         System.out.println(test.getClass()==Test.class);//一个类对应的class对象在内存中是唯一的
 6
 7         Class cls = Test.class;//字节码文件加载进内存，生成class对象，但是不会进行相关的初始化工作，不引起静态块的执行
 8         try {
 9
10             Field [] fields = cls.getDeclaredFields();
11             for (Field field : fields) {
12                 System.out.println(field);
13             }
14             Method [] methods = cls.getDeclaredMethods();
15             for (Method method : methods) {
16                 System.out.println(method);
17             }
18         } catch (SecurityException e) {
19             e.printStackTrace();
20         }
21     }
22 }
23 class Test{
24     public static int count=0;
25     private int age=20;
26     public String name="xm";
27     static{
28         System.out.println("类被加载");
29     }
30     public void test(){
31         System.out.println("sss");
32     }
33     private void call(){
34         System.out.println("hi");
35     }
36 }

类被加载
true
public static int com.test.demo.Test.count
private int com.test.demo.Test.age
public java.lang.String com.test.demo.Test.name
public void com.test.demo.Test.test()
private void com.test.demo.Test.call()

public class Demo {public static void main(String[] args) {Class intClass = int.class;Class<Integer> integerClass = int.class;integerClass = Integer.class;　　　　　Class<?> integerClz = Integer.class;

} }