java
基于JDK1.8
类型转换
/**
* 自带去0的操作，转换时
* while (i < len) {
* // Accumulating negatively avoids surprises near MAX_VALUE
* int digit = Character.digit(s.charAt(i++), radix);
* if (digit < 0 || result < multmin) {
* throw NumberFormatException.forInputString(s, radix);
* }
* result *= radix;
* if (result < limit + digit) {
* throw NumberFormatException.forInputString(s, radix);
* }
* result -= digit;
* }
*
*/
@Test
public void testTransferZero() {
String s = "000000001";
String s2 = "00000001.2";
Assertions.assertEquals(Integer.parseInt(s), 1);
Assertions.assertEquals(new BigDecimal(s2).toString(), "1.2");
}
正则
/**
* split函数不加-1等限制分隔数目的话，对于s这类的字符串，末尾的空白是不会纳入期内的
*
*
* 结果如下：
* [1, 2, 3]
* [1, 2, , 3]
* [1, 2, 3, ]
*/
@Test
public void testSplit() {
String s = "1,2,3,";
System.out.println(Arrays.toString(s.split(",")));
String s2 = "1,2,,3";
System.out.println(Arrays.toString(s2.split(",")));
System.out.println(Arrays.toString(s.split(",", -1)));
assert Arrays.asList(s.split(",", -1)).size() != 3;
}
异常
多级异常类
把粒度小的，需要优先catch的异常放前面做处理
try{
// doAnything()
}catch(SonException e){
// doAnything()
}catch(Exception exception){
// allException()
}
