java-StrinfBuffer

interface IContent{
    public void delete(int len);
    public  String reverse();
}

class StringContent implements IContent{
    private StringBuffer sb = new StringBuffer(26);
    
    public StringContent() {
        this.init();         //对内容进行初始化的操作
    }
    
    public void init() {  //生成数据
        Random random = new Random();
        for (int i = 0; i < 26; i++) {
        this.sb.append(‘a‘ + random.nextInt(26));
 //使用append(String str),StringBuffer的API方法。此方法将指定的字符串附加到此字符序列。random()用于返回一个随机数(字符)
        }
    }
    
    @Override
    public void delete(int len) {
        this.sb.delete(0,len);
    }
    
    @Override
    public String reverse() {
        return sb.reverse().toString();
    }
    
    public String toString() {
        return sb.toString();
    }
}

class Factory{  //工厂
    public static IContent getIntence() {
        return new StringContent();
    }
}

public class StringBuffer {    
    public static void main(String[] args) {
        IContent content = Factory.getIntence();
        System.out.println("初始化内容：" + content);
        System.out.println("转置内容：" + content.reverse());
        System.err.println("删除后剩余内容：" + content.delete(5));
    }

}