class MyObject {}
 
public class Test {
  public static void main(String[] args) {
    MyObject obj = new MyObject();
    obj.clone(); // Compile error.
  }
}

class MyObject2 {
  protected Object clone() throws CloneNotSupportedException {
    return super.clone();
  }
}
 
public class Test2 {
  public static void main(String[] args) throws CloneNotSupportedException {
    MyObject2 obj = new MyObject2();
    obj.clone(); // Compile OK.
  }
}

package 1
class MyObject3 {
protected Object clone() throws CloneNotSupportedException {
    return super.clone();
  }
}
 
package 2
public class Test3 extends MyObject3 {
  public static void main(String args[]) {
    MyObject3 obj = new MyObject3();
    obj.clone(); // Compile error.
    Test3 tobj = new Test3();
    tobj.clone();// Complie OK.
  }
}

public class TStatic {
  static int i;
 
  public TStatic() {
    i = 4;
  }
 
  public TStatic(int j) {
    i = j;
  }
 
  public static void main(String args[]) {
    System.out.println(TStatic.i);
    TStatic t = new TStatic(5); // 声明对象引用，并实例化。此时i=5
    System.out.println(t.i);
    TStatic tt = new TStatic(); // 声明对象引用，并实例化。此时i=4
    System.out.println(t.i);
    System.out.println(tt.i);
    System.out.println(t.i);
  }
}

0
5
4
4
4

class ClassA {
  int b;
 
  public void ex1() {}
 
  class ClassB {
    void ex2() {
      int i;
      ClassA a = new ClassA();
      i = a.b; // 这里通过对象引用访问成员变量b
      a.ex1(); // 这里通过对象引用访问成员函数ex1
    }
  }
}

class ClassA {
  static int b;
 
  static void ex1() {}
}
 
class ClassB {
  void ex2() {
    int i;
    i = ClassA.b; // 这里通过类名访问成员变量b
    ClassA.ex1(); // 这里通过类名访问成员函数ex1
  }
}

public class StaticCls {
  public static void main(String[] args) {
    OuterCls.InnerCls oi = new OuterCls.InnerCls();// 这之前不需要new一个OuterCls
  }
}
 
class OuterCls {
  public static class InnerCls {
    InnerCls() {
      System.out.println("InnerCls");
    }
  }
}

InnerCls

class Value {
  static int c = 0;
 
  Value() {
    c = 15;
  }
 
  Value(int i) {
    c = i;
  }
 
  static void inc() {
    c++;
  }
}
 
class Count {
  public static void prt(String s) {
    System.out.println(s);
  }
 
  Value v = new Value(10);
 
  static Value v1, v2;
  static {
    prt("in the static block of calss Count v1.c=" + v1.c + " v2.c="
       + v2.c);
    v1 = new Value(27);
    prt("in the static block of calss Count v1.c=" + v1.c + " v2.c="
       + v2.c);
    v2 = new Value();
    prt("in the static block of calss Count v1.c=" + v1.c + " v2.c="
       + v2.c);
  }
}
 
public class TStaticBlock {
  public static void main(String[] args) {
    Count ct = new Count();
    Count.prt("in the main:");
    Count.prt("ct.c=" + ct.v.c);
    Count.prt("v1.c=" + Count.v1.c + " v2.c=" + Count.v2.c);
    Count.v1.inc();
    Count.prt("v1.c=" + Count.v1.c + " v2.c=" + Count.v2.c);
    Count.prt("ct.c=" + ct.v.c);
  }
}

in the static block of calss Count v1.c=0 v2.c=0
in the static block of calss Count v1.c=27 v2.c=27
in the static block of calss Count v1.c=15 v2.c=15
in the main:
ct.c=10
v1.c=10 v2.c=10
v1.c=11 v2.c=11
ct.c=11