How to eliminate switch case or if-else ? and perform the below operations?

this below is the code :

public String evaluate() {

    if (this.data.equals("+")) {
      return String.valueOf(Double.parseDouble(this.children.get(0).evaluate()) + Double.parseDouble(this.children.get(1).evaluate()));
    } 

else if (this.data.equals("-")) {
      return String.valueOf(Double.parseDouble(this.children.get(0).evaluate()) - Double.parseDouble(this.children.get(1).evaluate()));
    } 

else if (this.data.equals("*")) {
      return String.valueOf(Double.parseDouble(this.children.get(0).evaluate()) * Double.parseDouble(this.children.get(1).evaluate()));
    } 

else {
      return String.valueOf(Double.parseDouble(this.children.get(0).evaluate()) / Double.parseDouble(this.children.get(1).evaluate()));
    }

  } 

the this.data value hold's the operand in form of String. Is there a way to eliminate the if-else altogether, decrease the lines of the code.? No to using switch case also.

Is there a way to convert string to operand in java.?