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## The `Comparable` Interface Type

- `object1.compareTo(object2)` returns
  - Negative number if `object1` less than `object2`
  - 0 if objects identical
  - Positive number if `object1` greater than `object2`
- `sort` method compares and rearranges elements
  `if (object1.compareTo(object2) > 0) . . .`
- `String` class implements `Comparable<String>` interface type: lexicographic (dictionary) order
- `Country` class: compare countries by area
  Ch4/sort1/Country.java
  Ch4/sort1/CountrySortTester.java

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