Problem with comparable generics

Question

Hi all,
I just started using generics and I cannot solve the following issue:
Here's the code snippet that gives me all the trouble:
public class BinaryLogicalExpression{
  private Comparable leftOperand;
  private Comparable rightOperand;
  public Boolean evaluate(){
    if(leftOperand.compareTo(rightOperand)<0)
    { return true; }
    else{ return false; }
} It gives an "unchecked" warning. Trying to suppress the warning, I did the following:
public class BinaryLogicalExpression<T>{
  private Comparable<T> leftOperand;
  private Comparable<T> rightOperand;
  public Boolean evaluate(){
    if(leftOperand.compareTo(rightOperand)<0)
    { return true; }
    else{ return false; }
  }which is obviously wrong because rightOperand should be of type T and not Comparable<T>. Apart from that, I am running out of ideas...

Answer 1

Try starting withpublic class BinaryLogicalExpression<T extends Comparable<T>>{
  private T leftOperand;
  private T rightOperand;