java如何将两个变量保存到一个向量中？

Question

class Buffer{
  public String name;
  public int id;
}

public class Main {
    public static void main(String[] args) {
      Vector<Buffer> vec = new Vector<Buffer>();
      getName = G.sIn.ReadInputLine();
      getID = G.sIn.ReadInt();
      vec.name.add(getName); // error
      vec.id.add( getID );  // error

    }
}

我是Java新手

然而，我想将两个变量保存到vector的name和id中并继续

现在，我不知道如何正确地实现

Answer 1

一个vector就像一个有序的列表，类似于arrayList。在您的实现中，它没有name或id属性。是你的Buffer类拥有它们。你把它声明为一个缓冲向量。所以这更正确：

class Buffer{
  public String name;
  public int id;
}

public class Main {
    public static void main(String[] args) {
      Vector<Buffer> vec = new Vector<Buffer>();
      getName = G.sIn.ReadInputLine();
      getID = G.sIn.ReadInt();
      Buffer buf = new Buffer();
      buf.name = getName;
      buf.id = getID;
      vec.add(buf);
    }
}

如果Buffer类有一个构造函数，那么创建它的速度会更快，而不需要buf变量和vec.add(new Buffer(getID, getName));

Answer 2

class Buffer{
  public String name;
  public int id;
}

public class Main {
    public static void main(String[] args) {
      Vector<Buffer> vec = new Vector<Buffer>();
      getName = G.sIn.ReadInputLine();
      getID = G.sIn.ReadInt();
      vec.name.add(getName); // error this can't work. vec isn't a Buffer
      vec.id.add( getID );  // error same problem    
    }
}

您需要存储缓冲区的实例，而不是它们的变量：

public class Main {
    public static void main(String[] args) {
      Vector<Buffer> vec = new Vector<Buffer>();
      Buffer tmp = new Buffer();
      vec.add(tmp); // this will work, you add a Buffer, but it will have default (0's) for the values
    }
}

使用您的输入，修改版本：

public class Main {
    public static void main(String[] args) {
      Vector<Buffer> vec = new Vector<Buffer>();
      Buffer tmp = new Buffer();
      tmp.name = G.sIn.ReadInputLine();
      tmp.id = G.sIn.ReadInt();
      vec.add(tmp); // this will work, you add a Buffer, but it will have default (0's) for the values
    }
}

不过，我建议大家仔细阅读一下命名惯例

Answer 3

vec本身不是Buffer类的实例，因此无法访问vec上Buffer类的数据成员或方法

vec是一个可以包含Buffer类实例的列表

Vector<Buffer> vec = new Vector<Buffer>();
getName = G.sIn.ReadInputLine();
getID = G.sIn.ReadInt();

// create an instance of Buffer class
Buffer buff = new Buffer();
buff.name = getName;
buff.id = getID;

// add the instance of Buffer class in vec
vec.add(buff);

但是，在类中包含public数据成员不是一个好的实践。Buffer类的所有数据成员都应该是private，并且应该使用constructor初始化

class Buffer{
  private String name;
  private int id;

  public Buffer(String name, int id) {
      this.name = name;
      this.id = id;
  }
}

public class Main {
    public static void main(String[] args) {
        Vector<Buffer> vec = new Vector<Buffer>();
        getName = G.sIn.ReadInputLine();
        getID = G.sIn.ReadInt();

        // create an instance of Buffer class
        Buffer buff = new Buffer(getName, getID);

        // add the instance of Buffer class in vec
        vec.add(buff);
    }
}

要访问或设置类的private数据成员的值，需要在Buffer类中定义Getter and Setter函数