Java by API/java.lang/Object

Object: finalize()

   <source lang="java">

public class MainClass {

 public static void main(String[] args) throws Exception {
   Object f = new Object() {
     public void finalize() {
       System.out.println("Running finalize()");
     }
   };
   Runtime.getRuntime().addShutdownHook(new Thread() {
     public void run() {
       System.out.println("Running Shutdown Hook");
     }
   });
   f = null;
   System.gc();
   System.out.println("Calling System.exit()");
   System.exit(0);
 }

}

 </source>
   
  
 
  

Object: getClass()

   <source lang="java">

/*

* Output: 

x is object of type: Class1 y is object of type: Class2 y"s superclass is Class1

*  
*/

class Class1 {

 int a;
 float b;

} class Class2 extends Class1 {

 double c;

} public class MainClass {

 public static void main(String args[]) {
   Class1 x = new Class1();
   Class2 y = new Class2();
   Class clObj;
   clObj = x.getClass(); // get Class reference
   System.out.println("x is object of type: " + clObj.getName());
   clObj = y.getClass(); // get Class reference
   System.out.println("y is object of type: " + clObj.getName());
   clObj = clObj.getSuperclass();
   System.out.println("y"s superclass is " + clObj.getName());
 }

}

 </source>
   
  
 
  

Object: getClass() (2)

   <source lang="java">

/*

* Output:

Public Methods:

a1
a2
* */

import java.lang.reflect.Method; import java.lang.reflect.Modifier; public class MainClass {

 public static void main(String args[]) {
   try {
     MyClass a = new MyClass();
     Class c = a.getClass();
     System.out.println("Public Methods:");
     Method methods[] = c.getDeclaredMethods();
     for (int i = 0; i < methods.length; i++) {
       int modifiers = methods[i].getModifiers();
       if (Modifier.isPublic(modifiers)) {
         System.out.println(" " + methods[i].getName());
       }
     }
   } catch (Exception e) {
     System.out.println("Exception: " + e);
   }
 }

} class MyClass {

 public void a1() {
 }
 public void a2() {
 }
 protected void a3() {
 }
 private void a4() {
 }

}

 </source>
   
  
 
  

Object: hashCode()

   <source lang="java">

/*

About to hashCode 2 objects.

MainClass@cf2c80 --> 13577344 java.awt.Color[r=68,g=136,b=204] --> -12285748

*/

public class MainClass {

 /** Some objects to hashCode() on */
 protected static Object[] data = { new MainClass(), new java.awt.Color(0x44, 0x88, 0xcc) };
 public static void main(String[] args) {
   System.out.println("About to hashCode " + data.length + " objects.");
   for (int i = 0; i < data.length; i++) {
     System.out.println(data[i].toString() + " --> " + data[i].hashCode());
   }
 }

}

 </source>
   
  
 
  

Object: notifyAll()

   <source lang="java">

/*

* Output:

Calling wait Calling notifyAll Done Done

*/

class SyncFlag {

 boolean flag;
 synchronized void k1() {
   if(flag == false) {
     flag = true;
     try {
       System.out.println("Calling wait");
       wait();
     }
     catch(Exception e) {
       e.printStackTrace();
     }
   }
   else {
     flag = false;
     System.out.println("Calling notifyAll");
     notifyAll();
   }
 }

} class MyThread extends Thread {

 SyncFlag flag;
 MyThread(SyncFlag k) {
   this.flag = k;
 }
 public void run() {
   flag.k1();
   System.out.println("Done");
 }

} public class MainClass {

 public static void main(String args[]) {
   SyncFlag k = new SyncFlag();
   new MyThread(k).start();
   new MyThread(k).start();
 }

}

 </source>
   
  
 
  

Object: toString()

   <source lang="java">

/*

* Output:
* Point[123456789,2147483647]
* */

class Point {

 int x, y;
 Point(int x, int y) {
   this.x = x;
   this.y = y;
 }
 public String toString() {
   return "Point[" + x + "," + y + "]";
 }

} public class MainClass {

 public static void main(String args[]) {
   Point p = new Point(123456789, 2147483647);
   System.out.print(p);
 }

}

 </source>
   
  
 
  

Object: wait(long timeout)

   <source lang="java">

public class Main {

 public static void main(String str[]) {
   final Object monitor = new Object();
   new Thread() {
     public void run() {
       try {
         synchronized (monitor) {
           System.out.println("10 seconds ...");
           monitor.wait(10000);
           System.out.println("Wait over");
         }
       } catch (Throwable t) {
         t.printStackTrace();
       }
     }
   }.start(); 
 }

}

 </source>