Java 如何将S更改为一组命令行 请帮助我如何将字符串更改为一组命令行。请考虑下面的代码: public class TestStringCommand{ public static void main(String[] args) { System.out.println("Change String to Command"); int a , b, c; String S = "a =1 ; b =2; c = a + b;"; //How to change S into a set of command lines // c will be 3 } }
一般来说,如果只是那些变量和加法,你可以去掉所有的空白,打开字符Java 如何将S更改为一组命令行 请帮助我如何将字符串更改为一组命令行。请考虑下面的代码: public class TestStringCommand{ public static void main(String[] args) { System.out.println("Change String to Command"); int a , b, c; String S = "a =1 ; b =2; c = a + b;"; //How to change S into a set of command lines // c will be 3 } },java,string,command,Java,String,Command,一般来说,如果只是那些变量和加法,你可以去掉所有的空白,打开字符 int a, b, c; Pattern integer = Pattern.compile("-?\\d+"); //fields 主要内容: processStatement: String[] parts = stmnt.split("="); if ( parts.length != 2) throw new IllegalArgumentException(...); int val = evaluateExpress
int a, b, c; Pattern integer = Pattern.compile("-?\\d+"); //fields
主要内容:
processStatement:
String[] parts = stmnt.split("=");
if ( parts.length != 2) throw new IllegalArgumentException(...);
int val = evaluateExpression(parts[1].substr(0, parts[1].length()-1)); //remove the ';'
setVar(parts[0], val);
setVar:
switch ( var ) {
case "a": a = val; break;
case "b": b = val; break;
...
default:
throw new IllegalArgumentException(...);
}
getVar:
switch ( var ) {
case "a": return a;
case "b": return b;
...
default:
throw new IllegalArgumentException (...)
}
evaluateExpression:
if (expr.isEmpty()) throw new ...;
int sum = 0; Matcher m = integer.matcher("");
for (String part : expr.split("+")) {
if (m.reset(part).matches()) {
sum += Integer.parseInt(part);
} else {
sum += getVar(part);
}
}
return sum;
我甚至没有尝试编译上面的代码,但这就是我的想法。你也可以使用虽然强大,但通常不是正确的方法
或者这就是你想要的
或者这就是你真正需要的
if (expr.isEmpty()) throw new ...;
int sum = 0; Matcher m = integer.matcher("");
for (String part : expr.split("+")) {
if (m.reset(part).matches()) {
sum += Integer.parseInt(part);
} else {
sum += getVar(part);
}
}
return sum;