Java-是否可以在数组中添加int和String？

Question

It's possible add an int and an String in the array ? I said in the same array.

Answer 1

No, Java is a strongly-typed language. So you cannot add a String and an int to the same array if the array is typed as either String or int .

However if your array is typed as Object , you can add a String and an Integer (an integer literal will be autoboxed) to that same array. This is not recommended and is probably a sign that you should think more about your design. The first question you need to ask yourself is why you need to do this. If you do have a valid reason, then it would be better to convert from one to the other instead of having an array typed as Object .

Having a catch-call array where you can shove in any object in a bad idea for many reasons:

• You are enforcing no separation between the objects. Are the objects actually related to each other? If so you type then using an interface or create an abstract class that each of the types extend.
• Since you have no separation between the objects, anything you pull out of the array is an Object . How would you know what it is? You need to inspect its type explicitly. This is an extremely cumbersome and unmaintainable design.
• You essentially end up losing type-safety and will not be able to benefit from type-mismatch errors that will show up during compilation. This will hide possible errors in your code where you may have forgotten to inspect the type, or where you are casting an object to the wrong type. This can lead to all kinds of nightmarish bugs.
• Your code is going to be littered with explicit checks and casts and will be unmaintainable (by you or anyone else).
• Your code leaks abstraction everywhere. No one can look at the array and realize what the array contains. Anyone who uses your code needs to remember an overwhelming amount of detail as to what types of objects the array can contain.
• Obfuscation is never a valid reason. Code should be clear, easy to read, easy to maintain, and easy to understand (for you and for anyone else who will read your code). Any code that looks obfuscated or is "clever" either needs to be rewritten or documented extensively to explain the reason for its "cleverness". As far as obfuscating the source, it is a non-issue since you're going to be distributing the .class files anyway. You can run that through a decompiler to look at the source code. There is nothing you can do at the source level to satisfactorily obfuscate your code; you're only going to make it difficult for you or anyone else to maintain. Obfuscation can be done at the byte-code level and so that doesn't really apply to this situation.

Answer 2

Yes it is possible, but it is not good practice.

Object[] myObjects = new Object[] {array1[i], array2[i], "name1", value1, value2, "name2",  value1, value....};

It must be array of objects

Answer 3

Strictly speaking: No.
Otherwise: Yes for most practical purposes:

Object[] array = { 42, "foo" };

Please note, that the 42 is not an int but an `Integer´. But due to autoboxing and unboxing you wont notice the difference. The tradeoff is of course performance and garbage collector overhead.

Also the array must be of type Object[] , not of type String[] nor of type int[] .

Answer 4

在字符串数组中，您可以输入“ 123”，然后在需要时将其转换为int。

Answer 5

You can't add a primitive types (including int) to an array with Objects such as String. However, autoboxing of int to Integer will make this possible if you declare an Object[] array.

Object[] array = new Object[2];
array[0] = "Hello";
array[1] = 42;

Though I wouldn't recommend doing this if modeling this String and int as attributes of a class would work.

Answer 6

Yes it definitely is possible, just have an array of raw objects.

For example:

Object[] arr = new Object[10];
arr[0] = 10; // boxed to Integer class
arr[1] = "foo"; // String class

Then you can use instanceof to determine the type of object stored at a particular index.

For example:

if (arr[0] instanceof Integer) ((Integer) arr[0]) += 10;

Note that this is not necessarily a good practise to get used to, but it does have applications.

Answer 7

You can use java.util.ArrayList to do this. You will need to make sure that you check carefully what you are getting when you pull items out though.