逗号和数组。字符串s[] = { “123”, “234”, };

JDK 1.6_07+包含一个名为VisualVM (bin/jvisualvm.exe)的应用程序，它是许多工具之上的一个漂亮的GUI。它似乎比JConsole更全面。

同一个类的实例可以访问其他实例的私有成员:

class Thing {
  private int x;

  public int addThings(Thing t2) {
    return this.x + t2.x;  // Can access t2's private value!
  }
}

语言级assert关键字。

The power you can have over the garbage collector and how it manages object collection is very powerful, especially for long-running and time-sensitive applications. It starts with weak, soft, and phantom references in the java.lang.ref package. Take a look at those, especially for building caches (there is a java.util.WeakHashMap already). Now dig a little deeper into the ReferenceQueue and you'll start having even more control. Finally grab the docs on the garbage collector itself and you'll be able to control how often it runs, sizes of different collection areas, and the types of algorithms used (for Java 5 see http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html).

不是Java语言的一部分，但是Sun的JDK附带的javap反汇编程序并不广为人知或被广泛使用。