title: no suitable method found for add()
body: <p>I am new to java
      "I get this error <strong>"no suitable method found for add()"</strong> when ever I try to run my program. Please help. What am I doing wrong? Please note that I am trying to learn how to use interface.</p>
  
  <p>Here's exxample:</p>
  
  <pre><code>public interface Calculate {
  
      int add(int a, int b);
  }
  
  public abstract class Maths extends MIDlet implements CommandListener, Calculate {
  
      private Display display;
      Form mainForm = new Form("Calculator");
      Form testForm = new Form("Results");
      TextField at = new TextField("A=", "", 10, TextField.NUMERIC);
      TextField bt = new TextField("B=", "", 10, TextField.NUMERIC);
      StringItem resultItem = new StringItem("Result =", "");
      Command addCommand = new Command("add", Command.SCREEN, 1);
  
      public Maths() {
          display = Display.getDisplay(this);
          mainForm.append(at);
          mainForm.append(bt);
          mainForm.addCommand(addCommand);
          testForm.append(resultItem);
          testForm.setCommandListener(this);
          mainForm.setCommandListener(this);
      }
  
      public void startApp() {
          Display.getDisplay(this).setCurrent(mainForm);
      }
  
      protected final void addOrderComponent(Component c) {
      }
  </code></pre>