尾随Java中的数组初始化内部逗号阵列 [英] Arrays with trailing commas inside an array initializer in Java
问题描述
阵列初始化可用于初始化在编译时阵列。如下图所示尾随逗号的初始化编译罚款。
Array initializers can be used to initialize arrays at compile-time. An initializer with trailing commas as shown below compiles fine.
int a[][] = {{1,2,} ,{3,4,} , {5,6,},}; //Trailing commas cause no compiler error
for(int i=0;i<a.length;i++)
{
for(int j=0;j<2;j++)
{
System.out.print(a[i][j]+"\t");
}
System.out.println();
}
输出:
1 2
3 4
5 6
也是合法的与一维数组作为明显与上述的讨论。
Also legal with one dimension arrays as obvious with the above discussion.
int[] b = {1, 2, 3, 4, 5, 6,}; //A trailing comma causes no compiler error
for(int i=0;i<b.length;i++)
{
System.out.print(b[i]+"\t");
}
输出:
1 2 3 4 5 6
即使下面是一个合法的语法和编译罚款。
Even the following is a legal syntax and compiles fine.
int c[][] = {{,} ,{,} , {,},};
之后和逗号之前的编译器应该期待一个恒定值(或其他初始化),
。这是怎么编?请问编译器只是忽略这些逗号或别的东西发生在这样的情况?
The compiler should expect a constant value (or another initializer) after and before a comma ,
. How is this compiled? Does the compiler simply ignore such commas or something else happens in such a scenario?
推荐答案
后面的逗号被忽略。从 Java规范:
The trailing comma is ignored. From the Java specification:
一个结尾逗号可以在数组初始化的最后EX pression后出现,将被忽略。
A trailing comma may appear after the last expression in an array initializer and is ignored.
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