11.26

学习了API和String Builder类

public class StringDemo01 {
public static void main(String[] args) {
//public String()：创建一个空白字符串对象，不含有任何内容
String s1 = new String();
System.out.println("s1:" + s1);

//public String(char[] chs)：根据字符数组的内容，来创建字符串对象
char[] chs = {'a', 'b', 'c'};
String s2 = new String(chs);
System.out.println("s2:" + s2);

//public String(byte[] bys)：根据字节数组的内容，来创建字符串对象
byte[] bys = {97, 98, 99};
String s3 = new String(bys);
System.out.println("s3:" + s3);

//String s = “abc”; 直接赋值的方式创建字符串对象，内容就是abc
String s4 = "abc";
System.out.println("s4:" + s4);
}
}

public class StringBuilderDemo01 {
public static void main(String[] args) {
//创建对象
StringBuilder sb = new StringBuilder();

//public StringBuilder append(任意类型)：添加数据，并返回对象本身
// StringBuilder sb2 = sb.append("hello");
//
// System.out.println("sb:" + sb);
// System.out.println("sb2:" + sb2);
// System.out.println(sb == sb2);

// sb.append("hello");
// sb.append("world");
// sb.append("java");
// sb.append(100);

//链式编程
sb.append("hello").append("world").append("java").append(100);

System.out.println("sb:" + sb);

//public StringBuilder reverse()：返回相反的字符序列
sb.reverse();
System.out.println("sb:" + sb);
}
}