different ways to add parenthesis leetcode #241, Java

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//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;

class Rextester
{  
    public static List<Integer> diffWaysToCompute(String input) {
        List<Integer> out = new ArrayList<>();
        try{
            out.add(Integer.parseInt(input));
            return out;
        }catch(NumberFormatException e){}
        
            
        for(int i = 0;i<input.length();i++){
            if(input.charAt(i)=='+' || input.charAt(i)=='-' || input.charAt(i)=='*'){

List<Integer> ret1 = diffWaysToCompute(input.substring(0,i));
                List<Integer> ret2 = diffWaysToCompute(input.substring(i+1));

for(int sum1:ret1){
                    for(int sum2:ret2){
                        int res = 0;
                        switch(input.charAt(i)){
                            
                            case '+': res = sum1+sum2;
                            break;
                            case '-': res = sum1- sum2;
                            break;
                            case '*': res = sum1* sum2;
                            break;
                        }
                        out.add(res);
                    }
                }
            }
        }
        return out;
    }
    
    public static void main(String args[])
    {
        System.out.println("Hello, World!");
        List<Integer> out = diffWaysToCompute("11");

for(int i:out)
            System.out.print(i+"  ");
    } 
}

[ + ] Show input
Compilation time: 0.84 sec, absolute running time: 0.16 sec, cpu time: 0.15 sec, memory peak: 18 Mb, absolute service time: 1,01 sec