1. String and Object Comparison Comparison operator

2. Equality Testing vs. Assignment  The = = operator tests for equality: if (x = = 0).. // if x equals zero  The = operator assigns a value to a variable: x = 0; // assign 0 to x  Don't confuse them.

3. String Comparison  Don't use = = for strings! if (input = = "Y") // WRONG!!!  Use equals method: if (input.equals("Y"))  = = tests identity, equals tests equal contents  Case insensitive test ("Y" or "y") if (input.equalsIgnoreCase("Y"))

4. public class StringExample { // instance variables - replace the example below with your own private String name; private String nickname; /** * Constructor for objects of class StringExample */ public StringExample() { // initialize instance variables name = "Robert"; nickname = name.substring(0,3); } public void displayNames() { if (nickname == "Rob") { System.out.println("The nickname is Rob"); } else { System.out.println("There is no nickname"); }

5. Object Comparison  = = tests for identity, equals for identical content Rectangle cerealBox = new Rectangle(5, 10, 20, 30); Rectangle oatmealBox = new Rectangle(5, 10, 20, 30); Rectangle r = cerealBox;  cerealBox != oatmealBox, but cerealBox.equals(oatmealBox)  cerealBox == r  Note: equals must be defined for the class

6. Object Comparison