JDK新特性
(1)JDK5(掌握)
装箱和拆箱
泛型
增强for
静态导入
可变参数
枚举
public enum Direction {
//FRONT, BEHIND, LEFT, RIGHT;
// FRONT("前"), BEHIND("后"), LEFT("左"), RIGHT("右");
FRONT("前") {
@Override
public void show() {
System.out.println("前");
}
},
BEHIND("后") {
@Override
public void show() {
System.out.println("后");
}
},
LEFT("左") {
@Override
public void show() {
System.out.println("左");
}
},
RIGHT("右") {
@Override
public void show() {
System.out.println("右");
}
};
private String name;
private Direction3(String name) {
this.name = name;
}
public String getName() {
return name;
}
public abstract void show();
}
public class EnumMethodDemo {
public static void main(String[] args) {
// int compareTo(E o)
Direction2 d21 = Direction2.FRONT;
Direction2 d22 = Direction2.BEHIND;
Direction2 d23 = Direction2.LEFT;
Direction2 d24 = Direction2.RIGHT;
System.out.println(d21.compareTo(d21));
System.out.println(d21.compareTo(d24));
System.out.println(d24.compareTo(d21));
System.out.println("---------------");
// String name()
System.out.println(d21.name());
System.out.println(d22.name());
System.out.println("--------------");
// int ordinal()
System.out.println(d21.ordinal());
System.out.println(d22.ordinal());
System.out.println("--------------");
// String toString()
System.out.println(d21.toString());
System.out.println(d22.toString());
System.out.println("--------------");
// <T> T valueOf(Class<T> type,String name)
Direction2 d = Enum.valueOf(Direction2.class, "FRONT");
System.out.println(d.getName());
System.out.println("----------------");
// values()
// 此方法虽然在JDK文档中查找不到，但每个枚举类都具有该方法，它遍历枚举类的所有枚举值非常方便
Direction2[] dirs = Direction2.values();
for (Direction2 d2 : dirs) {
System.out.println(d2);
System.out.println(d2.getName());
}
}
}
(2)JDK6(了解)
(3)JDK7(理解)
二进制的表现形式
用_分隔数据
switch语句可是用字符串
泛型推断(菱形泛型)
多catch的使用
自动释放资源的用法
(4)JDK8(了解)
Lambda表达式
Optional防止空指针的容器类
接口定义静态方法
String拼接的改进StringJoiner
Base64
.....
【jdk8的新特性用法在此不做主要说明，需要的小伙伴去这里看：（都是常用的）
https://blog.csdn.net/Smile_Sunny521/article/details/89846042
https://blog.csdn.net/Smile_Sunny521/article/details/89846163
https://blog.csdn.net/Smile_Sunny521/article/details/89845647
】
