package com.cdai.jvm; 
 
public class RuntimeConstantPool { 
 
  public static void main(String[] args) { 
 
    String s1 = new String("hello"); 
    String s2 = new String("hello"); 
    System.out.println("Before intern, s1 == s2: " + (s1 == s2)); 
     
    s1 = s1.intern(); 
    s2 = s2.intern(); 
    System.out.println("After intern, s1 == s2: " + (s1 == s2)); 
     
  } 
 
} 

package com.cdai.jvm.overflow; 
 
import java.lang.reflect.InvocationHandler; 
import java.lang.reflect.Method; 
import java.lang.reflect.Proxy; 
 
public class MethodAreaOverflow { 
 
  static interface OOMInterface { 
  } 
   
  static class OOMObject implements OOMInterface { 
  } 
   
  static class OOMObject2 implements OOMInterface { 
  } 
   
  public static void main(String[] args) { 
    final OOMObject object = new OOMObject(); 
    while (true) { 
      OOMInterface proxy = (OOMInterface) Proxy.newProxyInstance( 
          Thread.currentThread().getContextClassLoader(),  
          OOMObject.class.getInterfaces(),  
          new InvocationHandler() { 
            @Override 
            public Object invoke(Object proxy, Method method, Object[] args) 
                throws Throwable { 
              System.out.println("Interceptor1 is working"); 
              return method.invoke(object, args); 
            } 
          } 
      ); 
      System.out.println(proxy.getClass()); 
      System.out.println("Proxy1: " + proxy); 
       
      OOMInterface proxy2 = (OOMInterface) Proxy.newProxyInstance( 
          Thread.currentThread().getContextClassLoader(),  
          OOMObject.class.getInterfaces(),  
          new InvocationHandler() { 
            @Override 
            public Object invoke(Object proxy, Method method, Object[] args) 
                throws Throwable { 
              System.out.println("Interceptor2 is working"); 
              return method.invoke(object, args); 
            } 
          } 
      ); 
      System.out.println(proxy2.getClass()); 
      System.out.println("Proxy2: " + proxy2); 
    } 
  } 
 
} 

package com.cdai.jvm.overflow; 
 
import java.lang.reflect.Method; 
 
import net.sf.cglib.proxy.Enhancer; 
import net.sf.cglib.proxy.MethodInterceptor; 
import net.sf.cglib.proxy.MethodProxy; 
 
public class MethodAreaOverflow2 { 
 
  static class OOMObject { 
  } 
 
  public static void main(String[] args) { 
    while (true) { 
      Enhancer enhancer = new Enhancer(); 
      enhancer.setSuperclass(OOMObject.class); 
      enhancer.setUseCache(false); 
      enhancer.setCallback(new MethodInterceptor() { 
        @Override 
        public Object intercept(Object obj, Method method, 
            Object[] args, MethodProxy proxy) throws Throwable { 
          return method.invoke(obj, args); 
        } 
      }); 
      OOMObject proxy = (OOMObject) enhancer.create(); 
      System.out.println(proxy.getClass()); 
    } 
  } 
   
} 

package com.cdai.jvm.overflow; 
 
public class HeapOverflow { 
 
  private static final int MB = 1024 * 1024; 
   
  @SuppressWarnings("unused") 
  public static void main(String[] args) { 
    byte[] bigMemory = new byte[1024 * MB]; 
  } 
 
} 

package com.cdai.jvm.overflow; 
 
public class StackOverflow { 
 
  private static int stackDepth = 1; 
   
  public static void stackOverflow() { 
    stackDepth++; 
    stackOverflow(); 
  } 
   
  public static void main(String[] args) { 
    try { 
      stackOverflow(); 
    }  
    catch (Exception e) { 
      System.err.println("Stack depth: " + stackDepth); 
      e.printStackTrace(); 
    } 
  } 
   
}