按字母顺序排列 [英] Arranging by Alphabetical Order

问题描述

我是 Java 新手，我正在尝试按字母顺序排列术语数组列表.(术语定义为字符和整数)(例如 {Term('Z',4),Term('C',3),Term('Q',2) ...} )

I'm new to Java and I'm trying to arrange an arrayList of terms in alphabetical order. (A term is defined as a char and an int) (e.g. {Term('Z',4),Term('C',3),Term('Q',2) ...} )

我的代码如下:

    public Term nextElement()
{
    Term max = terms.get(0);
    char maxtest = max.getElement();
    for (int i = 1; i < terms.size(); i++){
        Term tester = terms.get(i);
        char maxtest2 = tester.getElement();
        if (maxtest2 > maxtest) {
            tester = max;
        }
    }
    return max;
}

为什么这不起作用?我该如何实现?我的 arrayList 被称为 term 填充类型 Term

Why isn't this working? and how do I accomplish this? My arrayList is called term filled with type Term

推荐答案

这行代码的问题.您的类不是 Comparable 的类型，因此，compareTo() 方法将compare 这两个对象在哪个属性或条件上compare ???>

Your problem with this line of Code. Your class is not a Type of Comparable So, On which property or criteria compareTo() method will compare these two objects ???

   res = maxtest.compareTo(maxtest2); //Your maxtest object is not Comparable Type.

您必须使您的类 Term 成为可比较类型.并且，根据您的需要覆盖方法 compareTo().

You must need to make your class Term Comparable type. and , Override the method compareTo() as per your need.

您没有提到类 Term 的变量或结构.所以，我假设你的班级有这种结构.

You have not mentioning the variable's or structure of your class Term . So, I am assuming that your class have such kind of Structure .

public class Term implements Comparable<Term> {
    private Character alpha;
   private int number;
   //getter and setters +Constructors as you specified
   ....
    ....
     ...
      .....
//  Now Set a criteria to sort is the Alphanumeric.
    @Override
    public int compareTo(Term prm_obj) {
        if (prm_obj.getAlpha() > this.alpha) {
            return 1;
        } else if (prm_obj.getAlpha() < this.alpha) {
            return -1;

        } else {
            return 0;
        }

    }

现在你的类变成了一个 comparable 类型.所以你可以应用 Collections.sort(Collection obj) 自动 sort 你的 ArrayList.

Now Your Class become a comparable Type. So you may apply Collections.sort(Collection obj) which automatically sort your ArrayList<Term>.

在这里我为此编写了一个演示.

Here I write a demo for this.

public static void main(String... args){

    List<Term> obj_listTerm = new ArrayList<>();
     //add all the data you given in question
    obj_listTerm .add(new Term('Z', 4)); 
    obj_listTerm .add(new Term('Q', 2));
    obj_listTerm .add(new Term('c', 3));

    // print without Sorting your Term ArrayList.
    System.out.println("This is the list unsorted: " + myTermList);
    // Sort Using Collections.sort() Method.

    Collections.sort(myTermList);

    // After applying sort() you may see your Sorted ArrayList.
    System.out.println("This is the list SORTED: " + myTermList);
}

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