JAVA创建顺序串类SeqString的新建串

以下是JAVA创建顺序串类SeqString的新建串的示例代码：

public class SeqString {
    private char[] data;

    public SeqString() {
        this.data = new char[0];
    }

    public SeqString(String str) {
        this.data = str.toCharArray();
    }

    public SeqString(char[] charArray) {
        this.data = charArray.clone();
    }

    public int length() {
        return this.data.length;
    }

    public char charAt(int index) {
        return this.data[index];
    }

    public SeqString substring(int beginIndex, int endIndex) {
        char[] sub = new char[endIndex - beginIndex];
        System.arraycopy(this.data, beginIndex, sub, 0, endIndex - beginIndex);
        return new SeqString(sub);
    }

    public SeqString concat(SeqString str) {
        char[] newData = new char[this.data.length + str.length()];
        System.arraycopy(this.data, 0, newData, 0, this.data.length);
        System.arraycopy(str.data, 0, newData, this.data.length, str.length());
        return new SeqString(newData);
    }

    public boolean equals(SeqString str) {
        if (this.data.length != str.length()) {
            return false;
        } else {
            for (int i = 0; i < this.data.length; i++) {
                if (this.data[i] != str.charAt(i)) {
                    return false;
                }
            }
            return true;
        }
    }

    public int indexOf(SeqString str) {
        for (int i = 0; i <= this.data.length - str.length(); i++) {
            if (this.substring(i, i + str.length()).equals(str)) {
                return i;
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        SeqString str1 = new SeqString();
        SeqString str2 = new SeqString("Hello");
        SeqString str3 = new SeqString(new char[] {'W', 'o', 'r', 'l', 'd'});
        
        System.out.println(str1.length()); // 0
        System.out.println(str2.charAt(1)); // e
        System.out.println(str3.substring(1, 3).equals(new SeqString("or"))); // true
        
        SeqString str4 = str2.concat(str3);
        System.out.println(str4.equals(new SeqString("HelloWorld"))); // true
        
        SeqString str5 = new SeqString("Hello");
        SeqString str6 = new SeqString("World");
        System.out.println(str5.equals(str6)); // false
        System.out.println(str4.indexOf(str3)); // 5
    }
}

在这个示例代码中，我们创建了一个SeqString类，实现了字符串的各种操作，包括新建空串、新建指定字符串的串、新建指定字符数组的串、获取字符串长度、获取指定位置字符、截取子串、串连接、判断相等、查找子串在主串中的位置等方法。在main方法中，我们对这些方法进行了测试。