Java数组比较 [英] Java Array Comparison

问题描述

在Java中的工作，让我们说我有两个对象，这要归功于 obj.getClass（）。IsArray的（），我知道都是数组。让我们进一步说，我想这两个数组相互比较 - 可能通过使用满足Arrays.equals 。有没有一种优雅的方式来做到这一点，而不诉诸一个大详尽的if / else树找出哪些满足Arrays.equals 的味道就要用？我在寻找的东西，比这少的碍眼的：

 
      如果（OBJ1的instanceof的byte [] && OBJ2的instanceof的byte []）{
         返回满足Arrays.equals（（字节[]）OBJ1，（字节[]）OBJ2）;
      }
      否则，如果（OBJ1的instanceof布尔[] && OBJ2的instanceof布尔[]）{
         ...
 

解决方案

您可以使用反射。

 公共静态布尔arrayEquals（对象ARR1，对象ARR2）抛出异常{
    类＆LT;＆GT; C = arr1.getClass（）;
    如果（！c.getComponentType（）。isPrimitive（））{
        C = [对象]类;
    }
    方法M = Arrays.class.getMethod（等于，C，C）;
    回报（布尔）m.invoke（NULL，ARR1，ARR2）;
}
 

反射仅用于查找在运行时没有你正在寻找避免碍眼正确的方法;实际满足Arrays.equals 方法应该跑得快pretty。

显然，量产版需要更强大的异常处理。您也可以使用 deepEquals（Object []对象，对象[]）而不是等于（Object []对象，对象[]）非基本数组。

Working within Java, let's say I have two objects that, thanks to obj.getClass().isArray(), I know are both arrays. Let's further say that I want to compare those two arrays to each other -- possibly by using Arrays.equals. Is there a graceful way to do this without resorting to a big exhaustive if/else tree to figure out which flavor of Arrays.equals needs to be used? I'm looking for something that's less of an eyesore than this:

      if (obj1 instanceof byte[] && obj2 instanceof byte[]) {
         return Arrays.equals((byte[])obj1, (byte[])obj2);
      }
      else if (obj1 instanceof boolean[] && obj2 instanceof boolean[]) {
         ...

解决方案

You can use reflection.

public static boolean arrayEquals(Object arr1, Object arr2) throws Exception {
    Class<?> c = arr1.getClass();
    if (!c.getComponentType().isPrimitive()) {
        c = Object[].class;
    }
    Method m = Arrays.class.getMethod("equals", c, c);
    return (Boolean) m.invoke(null, arr1, arr2);
}

Reflection is only used to find the right method at run-time without the eyesore you're looking to avoid; the actual Arrays.equals method should run pretty fast.

Obviously production version needs more robust exception handling. You may also want to use deepEquals(Object[], Object[]) instead of equals(Object[], Object[]) for non-primitive arrays.

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