java 我如何在java中将char作为命令行参数
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how can i take in a char as an command line argument in java
提问by Java Beans
how can i take in a char as an command line argument in java. I know how to do it for an integer and double which get converted to strings, but am stuck on character....I was thinking using charAt();
我如何在 java 中将字符作为命令行参数。我知道如何将整数和双精度转换为字符串，但我被困在字符上......我正在考虑使用 charAt();
double x = Double.parseDouble(args[0]);
// i know the below line doesnt make sense because charAt(c) expects 'c' to be the actual
// character and i have an index. but its what i wish to do(if it makes any sense).
char op = charAt(args[1]);
double y = Double.parseDouble(args[2]);
//for (Operation op : jumpTable)
System.out.printf("%f %s %f = %f%n", x, op, y, myArray[op].Compute(x, y));
thanks in advance guys!!! :))))
提前谢谢你们！！！:)))))
回答by mmccomb
You need to invoke the String argument's charAt method...
您需要调用 String 参数的 charAt 方法...
args[1].charAt(0)
回答by corsiKa
If you know your input string is EXACTLY one character long, use str.charAt(0);
如果您知道您的输入字符串正好是一个字符长，请使用 str.charAt(0);
回答by Hovercraft Full Of Eels
All command line arguments are Strings. So the solution is how to get a char from a String, and yes charAt(..) works well for this.
所有命令行参数都是字符串。所以解决方案是如何从字符串中获取字符，是的 charAt(..) 对此很有效。
edit: Your assumptions in your code are wrong since charAt takes an int input, the index of the char, not a char. You will want to read the String API to see the details.
编辑：您在代码中的假设是错误的，因为 charAt 需要一个 int 输入，即字符的索引，而不是字符。您将需要阅读 String API 以查看详细信息。
回答by Pravin Wadkar
Take an argument into String because the default JVM provides command line args as a String[] and you can get the first arg with
String s = args[0];Convert first letter of
String sinto acharwithchar ch = s.charAt(0);
将参数带入 String 因为默认 JVM 将命令行参数提供为 String[] 并且您可以获得第一个参数
String s = args[0];将的第一个字母
String s转换为charwithchar ch = s.charAt(0);
