Java'System.err.format''''n'後跟'System.out.println'，println打印在中間

Question

我對Java很新穎。

我使用的是Ubuntu 16.04，JDK 8u101，Netbeans8.1。

當試圖驗證碼：

public static void main(String[] args) { 
    System.err.format("1st Line %nPrints At 3rd Line,Shouldn't this be In 2nd Line "); 
    System.out.println("Shouldn't this be the third line,prints at 2nd line"); 
} 

輸出是：

This Prints At 1st Line 
Shouldn't this be the third line, but prints at 2nd line 
This Prints At 3rd Line, Shouldn't this be In 2nd Line 

爲什麼 「System.out.println」 打印在中間？ 不應該最後打印。

我 「%n」 試圖在最後& System.err.flush()這樣的：

System.err.format("1st Line %nPrints At 3rd Line,Shouldn't this be In 2nd Line%n"); 
System.err.flush(); 
System.out.println("Shouldn't this be the third line,prints at 2nd line"); 

還是相同的輸出。

Answer 1

你是不是調用println()電話和System.out和System.err之間flush()都（獨立）緩衝PrintStream（S）。

// and you need a %n on the end to make 3 lines. 
System.err.format("1st Line %nPrints At 3rd Line,Shouldn't this be In 2nd Line%n"); 
System.err.flush(); // <-- only needed if the previous write doesn't have 
        //  an implicit flush(); newline (%n) does. 
System.out.println("Shouldn't this be the third line,prints at 2nd line");