Java syntax
part 34/46 · 86.7 KB total
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public static void main(String[] args) {
CustomClass nc = new CustomClass();
hello();
//AbstractClass.hello();//also valid
}
}
Output:
org.dwwwp.test.AbstractClass: static block runtime
org.dwwwp.test.CustomClass: static block runtime
org.dwwwp.test.AbstractClass: instance block runtime
org.dwwwp.test.AbstractClass: constructor runtime
org.dwwwp.test.CustomClass: instance block runtime
org.dwwwp.test.CustomClass: constructor runtime
hello from org.dwwwp.test.AbstractClass
Enumerations
This language feature was introduced in J2SE 5.0. Technically enumerations are a kind of class containing enum constants in its body. Each enum constant defines an instance of the enum type. Enumeration classes cannot be instantiated anywhere except in the enumeration class itself.
enum Season {
WINTER, SPRING, SUMMER, AUTUMN
}
Enum constants are allowed to have constructors, which are called when the class is loaded:
public enum Season {
WINTER("Cold"), SPRING("Warmer"), SUMMER("Hot"), AUTUMN("Cooler");
Season(String description) {
this.description = description;
}
private final String description;
public String getDescription() {
return description;
}
}
Enumerations can have class bodies, in which case they are treated like anonymous classes extending the enum class:
public enum Season {
WINTER {
String getDescription() {return "cold";}
},
SPRING {
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