Java System.out.println 和 String 参数
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System.out.println and String arguments
提问by
When I write:
当我写：
System.out.println("Give grade: ", args[0]);
It gives the error:
它给出了错误：
The method println(String) in the type PrintStream is not applicable for the arguments (String, String).
PrintStream 类型中的方法 println(String) 不适用于参数 (String, String)。
Why is this so? However, when I try to write
为什么会这样？但是，当我尝试写
System.out.println("Give grade :");
System.out.println(args[0]);
No error shows. Is there a way I can write the above in one line of println()?
没有错误显示。有没有一种方法可以将上面的内容写在一行中println()？
采纳答案by David Ehrmann
The two that work only take one parameter, the one that fails takes two. Any chance you have a Javascript or Python background? Java enforces parameter type and count (like C).
两个有效的只需要一个参数，失败的一个需要两个。你有没有 Javascript 或 Python 背景的机会？Java 强制执行参数类型和计数（如 C）。
Try
尝试
System.out.println("Give grade: " + args[0]);
System.out.println("Give grade: " + args[0]);
or
或者
System.out.printf("Give grade: %s%n", args[0]);
System.out.printf("Give grade: %s%n", args[0]);
回答by merlin2011
One line. This just does the string concatenation inline.
一条线。这只是内联字符串连接。
System.out.println("Give grade: "+ args[0]);
回答by Abimaran Kugathasan
System.out.println(String text);internally calls PrintWriter#println()method and it expect one argument.
System.out.println(String text);内部调用PrintWriter#println()方法，它需要一个参数。
You can concatenate those to String literals and passed it like below.
您可以将它们连接到字符串文字并像下面一样传递它。
System.out.println("Give grade: " + args[0]);
回答by Luiggi Mendoza
From PrintWriter#printlnjavadoc, it notes that it takes a single argument.
从PrintWriter#printlnjavadoc 中，它指出它需要一个参数。
You can, instead, concatenate the data to form a single Stringparameter:
相反，您可以连接数据以形成单个String参数：
System.out.println("Give grade: " + args[0]);
You may want to check PrintWriter#printf:
您可能需要检查PrintWriter#printf：
System.out.printf("Give grade: %s\n", args[0]);
Note that the method above is available since Java 5 (but surely you're using Java 7 or 8).
请注意，上述方法从 Java 5 开始就可用（但您肯定使用的是 Java 7 或 8）。
回答by Thilo
Another method that you can use is format. It takes any number of arguments and formats them in various ways. The patterns should be familiar to you from other languages, they are pretty standard.
您可以使用的另一种方法是format. 它接受任意数量的参数并以各种方式格式化它们。您应该熟悉其他语言的模式，它们非常标准。
System.out.format("Give grade: %s%n", args[0]);
回答by Skyline
You do can either:
你可以：
System.out.println("Give grade: " + args[0]);
or in C-like style:
或类似 C 的风格：
System.out.printf("Give grade: %s%n", args[0]);
