java业务开发实用技巧一

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()
}

转载请注明作者及出处,本文作者为 tyrantqiao ,本文标题为 java业务开发实用技巧一 本文链接为 http://tyrantqiao.com/archives/c074f669/

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