How do I create an instance of a class in a method using Java?

In summary, the conversation discusses how to create an instance of a class within a method. The respondent suggests looking at examples on how to instantiate objects and mentions the use of Constructor.newInstance() for classes with multiple parameters. However, they also mention that abstract classes cannot be instantiated directly and must be derived into a concrete subclass first. A resource is provided for further understanding of abstract classes.
  • #1
Robben
166
2

Homework Statement



How do I create an instance of a class in a method?

Homework Equations



None

The Attempt at a Solution



I am a bit rusty whenever I think of instances. I always think of main method and objects when I see instance which gets me confused on what to do with the following example:

I have a abstract class, School, and inside School I have some methods that must preform some action on an instance. For example, there is a move() method that must move the instance of School. Another method named, personOld(), which returns whether or not an instance of School surpassed some determined age.
How do I create this instance?
 
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  • #3
Greg Bernhardt said:

Hm, in those examples they put the objects in the main method which is what I always think of when I see instance, but I have a class which isn't a main method which is what has gotten me confused.

Since my constructor, in my abstract School class, has many parameters then I must Constructor.newInstance()?

But how do I apply this?
 
  • #4

1. How do I create an instance of a class in a method using Java?

To create an instance of a class in a method using Java, you can use the new keyword followed by the class name and parentheses. This will call the class's constructor and create a new instance of the class.

2. Can I create an instance of a class without using the new keyword?

No, the new keyword is necessary to create an instance of a class in Java. It is used to allocate memory for the new object and call the constructor to initialize its fields.

3. How do I pass parameters to the constructor when creating an instance of a class?

You can pass parameters to the constructor by including them inside the parentheses after the class name when using the new keyword. These parameters must match the constructor's parameter list in the class definition.

4. Can I create multiple instances of a class in the same method?

Yes, you can create multiple instances of a class in the same method by using the new keyword more than once, each time with a different set of parameters if necessary.

5. Is it possible to create an instance of a class in one method and use it in another?

Yes, as long as the instance is declared as a class variable or passed as a parameter to the other method, it can be used in another method. This allows for greater flexibility and code reuse in your Java programs.

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