Java - 为什么以下代码打印出 "BAC"而不是 "ABC"？

Question

请帮助我理解这段代码。我是 Java 的新手。

// C.java
class C { 
  public static void main(String arg[]) { 
    System.out.println("A"+new C()); 
  } 
  public String toString() { 
    System.out.print("B"); 
    return "C"; 
  } 
}
// output:
// BAC  

Answer 1

评估是这样的:

Call println("A" + new C())
Since new C() hasn't been computed yet, we need to compute it, so...
Compute new C().toString()
    Print "B"
Print line with "A" + "C"

可以看到，打印语句的顺序是“B”、“A”、“C”