java - 如何在java中调用super之前运行一个函数？

Question

我有一个构造函数，它获取一个 HashSet 和一个 HashMap。我需要对一个 hashMAp 运行验证检查并将其与 hashSet 组合，因为“super”必须只接收一个 hashSet。我找不到解决方法，因为出现以下错误:cannot reference this before supertype constructor

例子:

public class A extends B {
  public A(HashSet<Obj> h1, HashMap<UID,Objects> m1) {
    super(new C (h1) ); //h1 should contain changes related to m1..
}

我想做这样的事情:

public class A extends B {
      public A(HashSet<Obj> h1, HashMap<UID,Objects> m1) {
        runMyFunc(h1,m1);
        super(new C (h1) );
    }



 runMyFunc(HashSet<Obj> h1, HashMap<UID,Objects> m1){
      //do checks
      //more checks...
      // if something then h1.setUid(m1.get(0))... 
      return h1;
   }

我想将构造函数转换为私有(private)的，然后像那样运行它:

public class A extends B {
  private A(HashSet<Obj> h1) {
    super(new C (h1) ); 
}

 public A(HashSet<Obj> h1, HashMap<UID,Objects> m1) {
     runMyFunc(h1,m1);
     this(h1);
 }

但它也没有用。

能请教一下吗？

Answer 1

只需让您的 runMyFunc static 并将其作为函数调用，您在 super 调用中使用返回值。这是允许的:

public class A extends B {
  public A(HashSet<Obj> h1, HashMap<UID,Objects> m1) {
     // Invoke as function rather than by itself on a separate line
     super(new C (runMyFunc(h1,m1)) );
  }

  // Make method static
  public static HashSet<Obj> runMyFunc(HashSet<Obj> h1, HashMap<UID,Objects> m1) {
     //do checks
     //more checks...
     // if something then h1.setUid(m1.get(0))... 
     return h1;
  }