Java中的动态数组 [英] Dynamic array in java

问题描述

我想做的是

...
int sum[];
...
for(int z.....){
   ...
   sum[z] = some_random_value;
   ...
}

但是它在行 sum [z] = ran; 处出现错误，提示变量 sum 可能尚未初始化.

But it gives an error at line sum[z]=ran; that variable sum might not have been initialized.

我尝试了 int sum [] = 0; 而不是 int sum []; ，但是即使这样也会出错.(我基本上是C程序员)

I tried int sum[] = 0; instead of int sum[]; but even that gave an error. (I am basically a C programmer)

推荐答案

在Java中无法使用动态大小的数组-您必须在声明大小之前先知道大小，或者对数组进行大小调整(会很痛苦).

An array of dynamic size isn't possible in Java - you have to either know the size before you declare it, or do resizing operations on the array (which can be painful).

相反，请使用 ArrayList< Integer> ，如果需要将其用作数组，则可以将其转换回去.

Instead, use an ArrayList<Integer>, and if you need it as an array, you can convert it back.

List<Integer> sum = new ArrayList<>();
for(int i = 0; i < upperBound; i++) {
    sum.add(i);
}
// necessary to convert back to Integer[]
Integer[] sumArray = sum.toArray(new Integer[0]); 

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