Java String

A Question

IMPORTANT

This Question

方法外的变量与其通过参数传递到方法内的变量 虽然名字以及值或者说地址是一样的，但这两者根本不是同一个变量。

Some Methods

 @Test
    public void testString(){
       String s1 = "78This904is325Truman9845Speaking";
       s1 = s1.replaceAll("\\d+", "_");
        System.out.println(s1);   // _This_is_Truman_Speaking
    }

  @Test
    public void testMatches(){
        String tel = "0558-2364015";
        boolean matches = tel.matches("0558-\\d{7,8}");
        System.out.println(matches);  // true
    }

@Test
    public void testSplit(){
        String s1 = "I_love_Villanelle";
        String[] split = s1.split("\\_");
        System.out.println(Arrays.toString(split));
    }

String -> byte[]

  @Test
    public void testByte(){
        String str1 = "Villanelle";
        byte[] bytes = str1.getBytes();
        System.out.println(Arrays.toString(bytes)); // [86, 105, 108, 108, 97, 110, 101, 108, 108, 101]
    }

Variable String -> StringBuffer & StringBuilder

Little Trick: there is letter f in StringBuffer, so, StringBuffer is Thread Safe

StringBuffer和 StringBuilder 默认的char[] 大小为16， 也可以指定， 扩容为 capacity * 2 + 2

Methods in StringBuffer

Java String

原文：https://www.cnblogs.com/nedrain/p/13285209.html