创建concat运算符将char数组添加到字符串中。打印字符串对象的引用变量

Question

到目前为止，如果我尝试使用concat运算符，我会得到这样的错误tester.java:14:cannot find symbol symbol：method concat（MyString）location：class MyString system.out.println（hello.concat（goodbye））；//打印“HelloGoodbye”

当我尝试打印MyString的“hello”对象时，我得到了MyString@558EE9D6，我觉得它接近工作了…

public class MyString

{
     private char[] charString;
     private String oneString;


      public  MyString(String string) 
      {
        this.oneString = string;


      }

//second constructor for overloading
    public MyString(char[] s) 
    {

        this.charString = s;
        this.oneString = charString.toString();
    }

//methods
    public String toString( char [] s)
    {
        return new String(s);
    }

    public char charAt(int i) {

        char [] temp = new char[oneString.length()];
        for ( int j = 0; j < oneString.length() ;  j++)
        temp[j] = oneString.charAt(i);
        return temp[i];
    }

    public String concat ( char[] s)
    {
        s.toString();
        String result = oneString + s;
        return result;
    }

    public String concat ( String s)
    {
        String result = oneString + s;
        return result;
    }


}

public class Tester{public static void main（String[]args）

    {
    MyString hello = new MyString("hello");
    System.out.println(hello);  // right now this prints MyString@558ee9d6
    System.out.println(hello.charAt(0));    // works, prints 'h'
    char[] arr = {'g','o','o','d','b','y','e' };
    MyString goodbye = new MyString(arr);
   // System.out.println(hello.concat(goodbye)); // i can't get this line to work
    System.out.println(hello.equals(goodbye)); // works, prints false
    System.out.println(hello.equals(hello));  //works, prints true
    }
    }

Answer 1

您正在尝试打印对象：

System.out.println(hello);  // right now this prints MyString@558ee9d6

在本例中，您的MyString类

将get方法设置为变量OneString。

public String getOneString() {return this.oneString;}

然后调用

System.out.println(hello.getOneString());

另一个问题

System.out.println(hello.concat(goodbye));

concat方法接收的是字符串，而不是MyString类

您可能想要这样做

System.out.println(hello.concat(goodbye.getOneString()));

或

public String concat ( MyString myS)
    {
        String s = myS.getOneString();
        String result = oneString + s;
        return result;
    }

最终结果：

public class Tester { public static void main (String[] args)

    {
    MyString hello = new MyString("hello");
    System.out.println(hello.getOneString());
    System.out.println(hello.getOneString().charAt(0)); 
    char[] arr = {'g','o','o','d','b','y','e' };
    MyString goodbye = new MyString(arr);
    System.out.println(hello.concat(goodbye.getOneString()));
    System.out.println(hello.equals(goodbye)); // works, prints false
    System.out.println(hello.equals(hello));  //works, prints true
    }
    }