Java意外类型错误必需变量找到值

Question

public boolean replaceEventAt(String eventStr, int position){
  boolean answer = false;

  if((position > 0) && (position <= events.size())){
     events.get(position - 1) = eventStr;
     answer = true;
  }

  return answer;
}

Error on fifth line where Java complains that position is a value not a variable please help

Answer 1

An assignment operates between what is known as an lvalue and an rvalue .

lvalue stands for left-hand-side-value.

rvalue stands for right-hand-side-value.

The rvalue can be many things, like a variable, a constant, a function call expression, etc, but the left side must be assignable, so it cannot be a constant or a function call.

In your case, your rvalue is a function invocation; that won't work. The compiler error message is saying exactly that.

If we knew what you are trying to do we could perhaps explain more, but it is unclear from the code that you posted that it is that you want to accomplish. Perhaps events is some collection, and you want to set the element at position position - 1 to eventStr , in this case you would probably want events.set( position - 1, eventStr );

Answer 2

Left hand side must be a variable (ie we should be able to assign a value to it ). But in your case it is performing a get operation So it is throwing an Error