Question

我是Java继承的新手。请参阅我的父类名为Term：

的代码

public class Term {

  public String value;
  public void setValue(String value)
  {
    this.value=value;
  }

  public String getValue()
  {
    return value;
  }

}

现在，类OperatorTerm扩展了术语

public class OperatorTerm extends Term {

  public static Operator type;

  public static boolean equals(String value)
  {
    String regex="(\\++)|(-+)|\\*|/";
    boolean isOperand=value.matches(regex);
    return isOperand;
  }

  public void assignType(String value)
  {
    if(value.equals("+"))
      type=Operator.ADD;
    else if(value.equals("-"))
      type=Operator.SUBTRACT;
    else if(value.equals("*"))
      type=Operator.MULTIPLY;
    else if(value.equals("/"))
      type=Operator.DIVIDE;
    else if(value.equals("++"))
      type=Operator.INCREMENT;
    else
      type=Operator.DECREMENT;
    }
  }

我正在另一个类中创建一个这样的OperatorTerm对象：

public static Term getTerm(String termValue)
{
  Term newTerm=null;
  if(ValueTerm.equals(termValue))
    newTerm=new ValueTerm();
  else if(ReferenceTerm.equals(termValue))
    newTerm=new ReferenceTerm();
  else if(OperatorTerm.equals(termValue))
  {
    newTerm=new OperatorTerm();
  }
  return newTerm;
}

在最后一个elseif语句中，我想执行以下newTerm.assignType。 assignType是OperatorTerm类中的一个方法，但它不存在于Term类中。我无法这样做，我想知道是否有人可以指导我如何使用newTerm来访问OperatorTerm类的方法

我正在使用

创建重写类的对象

Answer 1

#!/usr/bin/python

import sys

# gets list of annotations
def get_annos(infile):
    with open(infile, 'r') as fh:  # makes sure the file is closed properly
        annos = []
        for line in fh:
            annos.append( line.split('\t')[5] ) # added tab as separator

    return annos

# replaces extra info on each header with correct annotation
def add_annos(infile1, infile2, outfile):
    annos = get_annos(infile1) # contains list of annos
    with open(infile2, 'r') as f2, open(outfile, 'w') as output:
        for line in f2:
            if line.startswith('>'):
                line_split = list(line.split()[0]) # split line on whitespace and store first element in list
                line_split.append(annos.pop(0)) # append data of interest to current id line
                output.write( ' '.join(line_split) + '\n' ) # join and write to file with a newline character
            else:
                output.write(line)

anno = sys.argv[1]
seq = sys.argv[2]
out = sys.argv[3]

add_annos(anno, seq, out)
get_annos(anno)

Answer 2

如果你需要调用方法＆＃34; newTerm.assignType＆＃34;在getTerm方法中，也许你只需要返回和/或创建正确的子对象：

public static Term getTerm(String termValue)
    {
        // Term newTerm=null;
        if(ValueTerm.equals(termValue))
            return new ValueTerm();
        else if(ReferenceTerm.equals(termValue))
            return new ReferenceTerm();
        else if(OperatorTerm.equals(termValue))
        {
            OperatorTerm newTerm=new OperatorTerm();
            newTerm.assignType("+");
            return newTerm;
        }
        // return newTerm;
    }

通常，如果您使用的对象是父对象，则不能使用在扩展类中创建的方法。

希望我的答案对你想做的事情有用。

Answer 3

else if(OperatorTerm.equals(termValue))
{
    newTerm = new Operatorterm();
    ((OperatorTerm) newTerm).assignType(value);
}

我个人会这样做

else if(OperatorTerm.equals(termValue))
{
    OperatorTerm ot = new OperatorTerm();
    ot.assignType(value);
    return ot;
}

为其他人做同样的事。

在Java中，如何从重写类的实例调用重写类的方法

3 个答案: