Questions about the * number when Java passes a value to the Main method

The existing requirements are as follows:

The value of a simple expression is obtained by means of a cmd.

For example, enter Java Expression 3 + 4

The results are: 7

Code:

Import Java.text.DecimalFormat;

public class Expression {

public static void Main (string[] args) throws Exception {
if (args = = NULL | | Args.length! = 3) {

MyException is simply a succession of exception, which can be regarded as exception. (This is because of the special requirements on the topic, please ignore ...) ）
throw new MyException ("Incorrect parameter format");
}

Left-hand operand in expression
Double left = double.valueof (Args[0]);

Operator: + 、-、 *,/
String operate = args[1];

Right operand
Double right = double.valueof (args[2]);
Result of Operation
Double result;

Switch (operate) {
Case "+":
result = left + right;
Break

Case "-":
result = Left-right;
Break

Case "*":
result = left * right;
Break

Case "/":
result = Left/right;
Break

Default
throw new MyException ("Incorrect parameter format");
}

System.out.println (New DecimalFormat ("0.00"). Format (result);
}
}

Operation Result:

Found problems with the program only if the operator is an * number

Modify the program to output the args array entered as: 2 * 3 o'clock

if (args! = null) {
for (int i = 0;i < args.length;i++) {
System.out.println (Args[i]);
}
}

found that when the input parameter is ' * ', there is a lot of data in the args array

The comparison found that the names of all the files under the Java file path were duplicated

So, when you pass a value to the Main method, enter the * number to add the names of all the files in the Java file path to the args array.

The question about the * number when Java passes a value to the Main method