java - String.valueOf(int i) 和只打印 i 的区别

Question

请看下面的代码片段:

int count = 0;
String query = "getQuery"; 
String query1 = "getQuery";
final String PARAMETER = "param";

query += "&" + PARAMETER  + "=" + String.valueOf(count);
query1 += "&" + PARAMETER  + "=" + count;
System.out.println("Cast to String=>"+query);
System.out.println("Without casting=>"+query1);

两个输出完全一样。 所以我想知道，当我们仅使用 count 就可以获得相同的结果时，为什么要使用它。

我得到了一些链接，但没有发现完全相同的混淆。

Answer 1

这在 JLS - 15.18.1. String Concatenation Operator + 中有很好的解释:

If only one operand expression is of type String, then string conversion (§5.1.11) is performed on the other operand to produce a string at run time.

您应该注意以下几点:

The + operator is syntactically left-associative, no matter whether it is determined by type analysis to represent string concatenation or numeric addition. In some cases care is required to get the desired result.

如果你写 1 + 2 + "fiddlers" 结果将是

3 fiddlers

但是，编写 "fiddlers "+ 1 + 2 会产生:

fiddlers 12