Java：传入一个字符串并将其存储

Question

How would I create a method that has the input of a string and output of all the strings that were input into it like a super string?

for example in the main class:

a= "fido"
b= "rufus"
c= "dog"

superString(a); 
superString(b); 
superString(c); 

System.out.println(superString());  should be "fidorufusdog"

so far I have=

public static String superString (String sb) {
    StringBuilder ssb = new StringBuilder(32);
    ssb = ssb.append(sb);
    return ssb.toString();
}

My code below is what I am working on for a stock simulator:

public class Operators {
  public static void operate(double price, double low, String company){
    double percent = (price/low-1)*100;
    double rpercent = Math.round(percent * 100.0) / 100.0; 
    StringBuilder sb = new StringBuilder(32);

    if(rpercent <= 10) {
      sb.append(company + " is trading at:");
      sb.append("the current price is:  " + price);
      sb.append("the 52 week low is:  " + low);
      sb.append("percent of 52 week low is:  " + rpercent);
    }
  }
}

The operate method is called in a for loop in my main method 506 times and I would like to take all 506 sb string and create a super string of all the results

Answer 1

Declare that string builder as the static member containing class and initialize it only once

static StringBuilder ssb;
public static String superString (String sb) {
    if(ssb == null)
          ssb = new StringBuilder(32);
    ssb = ssb.append(sb);
    return ssb.toString();
}

Answer 2

I hope I do not underestimate the depth of the question or have your question wrong, but to me it sounds like you are asking for the static keyword?

class SomeClass {

    static StringBuilder accumulator = new StringBuilder();

    public String superString (String sb) {
        SomeClass.accumulator.append(sb);
        return ssb.toString();
    }

}

This is simple usecase of the Java static keyword. Since accumulator is declared static there will be a single instance of the variable. And this single instance will be accessed by instances of the class SomeClass. For example:

SomeClass a;
SomeClass b;

a.superString("aaa");
b.superString("bbb");

// now accumulator.toString() returns "aaabbb"

Answer 3

For this kind of probelm you've two choice :

1. Simple : create a static variable in the Java class, and manipulate it.
2. improve : create a design model which support your need.

Ex 1 :

public class Operators {

    private static String text ="";

    public static String superString(String sb) {        
        if (sb != null) {
             text = text.concat(sb);
        }
        return text;
    }

}

Ex 2 : you can use a Collecion or a List of strings.

Answer 4

This is poor OOP design. You would be much better off creating a class for Stock objects and overriding toString in the Stock class(or creating some other simple output method). Then add each instance of Stock to an array and call the each object's toString (or other output method you defined).