多级字符串拆分

Question

So My requirement is an extension of this: Obtaining the split value after java string split

My input string is something like this:

FEES_1 > 100 AND FEES_2 <= 200 OR FEES_3 <= 500

I need to iterate over individual conditions and I would like to know which is the conditional operator seperating each conditions.

Expected Output:-

Iteration 1:
Operands: [FEES_1 ,  100 ]
Relational Operator: >
Conditional Operator: null

Iteration 2:
Operands: [FEES_2 ,  200 ]
Relational Operator: <=
Conditional Operator: AND

Operands: [FEES_3 ,  500 ]
Relational Operator: <=
Conditional Operator: OR

Now I can find Operands and Relational Operator using the answer given in above link. But how can I find the Conditional Operator and print it in above format?

Answer 1

You can use this code which contains regex to parse the values as per your needs.

public static void main(String[] args) {
    String str = "FEES_1 > 100 AND FEES_2 <= 200 OR FEES_3 <= 500";
    Pattern p = Pattern.compile("(?:^|(AND|OR))\\s*(\\w+)\\s+([<>]=?)\\s+(\\d+)\\s*(?=(AND|OR|$))");
    Matcher m = p.matcher(str);
    for (int i = 0; m.find(); i++) {
        System.out.println("Iteration " + (i + 1) + ":");
        System.out.println(String.format("Operands: [%s ,  %s ]", m.group(2), m.group(4)));
        System.out.println("Relational Operator: " + m.group(3));
        System.out.println("Conditional Operator: " + m.group(1));
        System.out.println();
    }
}

This code gives following output matching exactly as you wanted.

Iteration 1:
Operands: [FEES_1 ,  100 ]
Relational Operator: >
Conditional Operator: null

Iteration 2:
Operands: [FEES_2 ,  200 ]
Relational Operator: <=
Conditional Operator: AND

Iteration 3:
Operands: [FEES_3 ,  500 ]
Relational Operator: <=
Conditional Operator: OR

Answer 2

@Warren if you are 100% sure that input string is of this format, then you can simply do something like this. It is much simpler and straight forward, no need of any regex.

String[] parts = string.split(" ");

split the input string by spaces and then for each successive iteration you can print like this

int end = (parts.length + 1)/4;
for(int i =0;i<end;i++){
    System.out.println("Iteration : " + (i+1));

    System.out.println("Operands: [ " + parts[4*i] + " , " + parts[4*i + 2] + "]");

    System.out.println("Relational Operator: " + parts[4*i + 1]);

    System.out.println("Conditional Operator: " + ((i>0)?parts[4*i - 1]:null));
}