java7和java8新特性

[做梦的梦想家]

Java7:

1，switch中可以使用字串了
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String s = "test";
switch (s) {
case "test" :
System.out.println("test");
case "test1" :
System.out.println("test1");
break ;
default :
System.out.println("break");
break ;
}


2.运用List<String> tempList = new ArrayList<>(); 即泛型实例化类型自动推断

3.语法上支持集合，而不一定是数组

final List<Integer> piDigits = ;
4.新增一些取环境信息的工具方法
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File System.getJavaIoTempDir() // IO临时文件夹
File System.getJavaHomeDir() // JRE的安装目录
File System.getUserHomeDir() // 当前用户目录
File System.getUserDir() // 启动java进程时所在的目录5


5.Boolean类型反转，空指针安全,参与位运算
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Boolean Booleans.negate(Boolean booleanObj)
True => False , False => True, Null => Null
boolean Booleans.and(boolean array)
boolean Booleans.or(boolean array)
boolean Booleans.xor(boolean array)
boolean Booleans.and(Boolean array)
boolean Booleans.or(Boolean array)
boolean Booleans.xor(Boolean array)




6.两个char间的equals
boolean Character.equalsIgnoreCase(char ch1, char ch2)

7.安全的加减乘除
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int Math.safeToInt(long value)
int Math.safeNegate(int value)
long Math.safeSubtract(long value1, int value2)
long Math.safeSubtract(long value1, long value2)
int Math.safeMultiply(int value1, int value2)
long Math.safeMultiply(long value1, int value2)
long Math.safeMultiply(long value1, long value2)
long Math.safeNegate(long value)
int Math.safeAdd(int value1, int value2)
long Math.safeAdd(long value1, int value2)
long Math.safeAdd(long value1, long value2)
int Math.safeSubtract(int value1, int value2)


8.map集合支持并发请求，且可以写成 Map map = {name:"xxx",age:18};

[街头小贩]

java8变化挺大的