如何声明未知大小的字符串数组[]（JAVA）
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/39226737/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to declare string array[] of unknown size (JAVA)
提问by tin
I want my String[] array;to be static but I still don't know it's size.
我希望我String[] array;是静态的，但我仍然不知道它的大小。
Is there any way to declare string array of unknown size? As much as possible I don't want to use ArrayList
有没有办法声明未知大小的字符串数组？我尽可能不想使用 ArrayList
采纳答案by Jiri Tousek
You don't need to know the array size when you declareit
你并不需要知道数组的大小，当你宣布它
String[] myArray;
but you do need to know the size when you initializeit (because Java Virtual Machine needs to reserve a continuous chunk of memory for an arrayupfront):
但是在初始化时确实需要知道大小（因为Java 虚拟机需要预先为数组保留一块连续的内存）：
myArray = new String[256];
If you don't know what the size will need to be in the moment you initialize it, you need a List<String>, or you'll be forced to make your own implementation of it (which is almost certainly worse option).
如果您在初始化时不知道需要多大的大小，则需要一个List<String>，否则您将被迫自己实现它（这几乎肯定是更糟糕的选择）。
回答by steveman
No, it needs to be declared, and thus have a length before you can set elements in it.
不，它需要声明，因此在您可以在其中设置元素之前有一个长度。
If you want to resize an array, you'll have to do something like: Expanding an Array?
如果要调整数组大小，则必须执行以下操作：展开数组？
回答by MiOnIs
回答by huseyin tugrul buyukisik
String [] array = new String[1];
it will be garbage collected later after you init with a real array n elements.
在使用真实数组 n 个元素进行初始化后，它将在稍后被垃圾收集。
array = new String[n];
ofcourse it has a performance decrease but it should be non-importance unless you repeat same for many different arrays.
当然，它会降低性能，但除非您对许多不同的阵列重复相同的操作，否则它应该不重要。
回答by Vaibhav Walke
Using Java.util.ArrayList or LinkedList is the usual way of doing this. With arrays that's not possibleas I know.
使用 Java.util.ArrayList 或 LinkedList 是执行此操作的常用方法。据我所知，使用数组是不可能的。
Example:
例子：
List unindexedVectors = new ArrayList();
列出 unindexedVectors = new ArrayList();
unindexedVectors.add(2.22f);
unindexedVectors.add(2.22f);
unindexedVectors.get(2);
unindexedVectors.get(2);
回答by Ray Mulgrew
My apologies to the nay-say-ers, this can be done easily.
我向反对者道歉，这很容易做到。
import java.util.Random;
public class Roll_2 {
static Random random = new Random();
public static void main(String[] args) {
int[] variableArray1 = init(random.nextInt(9)); // random size
int[] variableArray2 = init(random.nextInt(9)); // random size
int[] variableArray3 = init(random.nextInt(9)); // random size
randomaize(variableArray1); // randomize elements
randomaize(variableArray2); // randomize elements
randomaize(variableArray3); // randomize elements
print(variableArray1); // print final
print(variableArray2); // print final
print(variableArray3); // print final
}
private static int[] init(int x) {
int[] arr = new int[x];
return arr;
}
private static void print(int[] body) {
System.out.print("[");
for (int i=0;i<body.length;i++) {
System.out.print(body[i]);
if (i<body.length-1) System.out.print(" ");
}
System.out.println("]");
}
private static void randomaize(int[] body) {
for (int i=0;i<body.length;i++) {
body[i] = random.nextInt(9);
}
}
}
Sample Run 1: [1 7 2] [5 2 8 6 8 3 0 8] []
Sample Run 2: [2 5 6 8 0 7 0 6] [0 0 1] [2 1 2 1 6]
Sample Run 3: [8 3 3] [7] [1 3 7 3 1 2]
样品运行 1：[1 7 2] [5 2 8 6 8 3 0 8] []
样品运行 2：[2 5 6 8 0 7 0 6] [0 0 1] [2 1 2 1 6]
样品运行 3：[8 3 3] [7] [1 3 7 3 1 2]
