java final 、finally与finalize的区别

final：在java中，final一般是指不可变的，是一个修饰符，可以修饰常量、方法、类，

public class TestOne{
	final int MAX_ONE=1;
	public void test(){
		MAX_ONE=2;//在这里是错误的，变量被final修饰后不能再赋值
	}
	}

public class TestOne{
	final int MAX_ONE=1;
	public final void test(){
		String name="sdf";
	}
	
	
	}
class TestTwo extends TestOne{
	public final void test(){
		String name="sabc";//在这里是错误的，继承后final方法不能被重写
	}
	
}

public final class TestOne{
	final int MAX_ONE=1;
	public final void test(){
		String name="sdf";
	}
	
	
	}
class TestTwo extends TestOne{//在这是错误的，final类不能被继承

	
}

finally：finally是异常处理的一部分，

Java 中的 Finally 关键一般与try一起使用，在程序进入try块之后，无论程序是因为异常而中止或其它方式返回终止的，finally块的内容一定会被执行 。

以下实例演示了如何使用 finally 通过 e.getMessage() 来捕获异常（非法参数异常）

public class ExceptionDemo2 {
   public static void main(String[] argv) {
      new ExceptionDemo2().doTheWork();
   }
   public void doTheWork() {
      Object o = null;
      for (int i=0; i<5; i++) {
         try {
            o = makeObj(i);
         }
         catch (IllegalArgumentException e) {
            System.err.println
            ("Error: ("+ e.getMessage()+").");
            return;   
         }
         finally {
            System.err.println("都已执行完毕");
            if (o==null)
            System.exit(0);
        }
        System.out.println(o); 
      }
   }
   public Object makeObj(int type) 
   throws IllegalArgumentException {
      if (type == 1)  
      throw new IllegalArgumentException
      ("不是指定的类型： " + type);
      return new Object();
   }
}

finalize:finalize-方法名。Java 技术允许使用 finalize() 方法在垃圾收集器将对象从内存中清除出去之前做必要的清理工作。

package Initialization;
class Tank{
        int howFull = 0;
        Tank() { this(0);}
        Tank(int fullness){
        howFull = fullness;
}
    void sayHowFull(){
        if(howFull == 0)
        System.out.println("Tank is empty!");
        else
        System.out.println("Tank filling status : " + howFull);
}
    void empty(){
    howFull = 0;
}
    protected void finalize(){
    if(howFull != 0){
    System.out.println("Error: Tank not empty." + this.howFull);
}
//Normally,you'll also do this:
//Super.finalize(); //call the base-class version
}
}
        public class TankTest {
    public static void main(String[] args) {
    Tank tank1 = new Tank();
    Tank tank2 = new Tank(3);
        Tank tank3 = new Tank(5);
    tank2.empty();
        //Drop the reference,forget to cleanup:
    new Tank(6);
        new Tank(7);
    System.out.println("Check tanks:");
        System.out.println("tank1:");
    tank1.sayHowFull();
        System.out.println("tank2:");
    tank2.sayHowFull();
    System.out.println("tank3");
    tank3.sayHowFull();
    System.out.println("first forced gc()");
    System.gc();
    System.out.println("try deprecated runFinalizerOnExit(true)");
    System.runFinalizersOnExit(true);
    System.out.println("last forced gc():");
    System.gc();
}
}