[英]Console based command processing: Mapping string to enum in java
對於我的Java控制台應用程序,我需要使用用戶給定的參數調用一組函數。 我的操作O1,O2,... O5被定義為枚舉
enum Operations {O1, O2, O3, O4, O5};
我需要讀取用戶輸入args [0]並調用函數F1,F2,... F5。
例如,用戶將給出:
>java MyApp O1 5 6
為此,我想我需要將sting(args [0])映射到枚舉,以便我可以使用switch select。 這個怎么做?
例
Operations oper = Enum.valueOf(Operations.class, args[0]);
如果沒有與args[0]
匹配的枚舉值,將拋出異常
我想使用chuk lee的線索,您可以在這里提出我的出色程序。
public class Main {
public static void main(String[] args) {
if(args.length < NUMBER_OF_OPERATORS){
throw new IllegalArgumentException(INSUFFICIENT_OPERANDS);
}
Operator operator = Enum.valueOf(Operator.class,
args[OPERATION_NAME].toUpperCase());
System.out.println(operator.operate(args[FIRST_OPERAND],
args[SECOND_OPERAND]));
}
private enum Operator {
ADD,SUBSTRACT,MULTIPLY,DIVIDE;
public String operate(String aString, String bString) {
int a = Integer.valueOf(aString);
int b = Integer.valueOf(bString);
int out = 0;
switch(this) {
case ADD : out = a + b; break;
case SUBSTRACT : out = a - b; break;
case MULTIPLY : out = a * b; break;
case DIVIDE : out = a / b; break;
default: throw new UnsupportedOperationException();
}
return String.valueOf(out);
}
}
private static final int NUMBER_OF_OPERATORS = 3;
private static final int OPERATION_NAME = 0;
private static final int FIRST_OPERAND = 1;
private static final int SECOND_OPERAND = 2;
private static final String INSUFFICIENT_OPERANDS =
"Insufficient operads to carry out the operation.";
}
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