我做错了什么？ 静态错误[Java]

Question

It refrences a error that I cannot use static when I used my function generatecode() I wanted to see if I did my split correctly. I am new and still need a bit of help. I've seen something on creating a new class via in this case: TestFile variable = new TestFile(); I had no idea what this means. Thanks!

    public class TestFile {

String[] preps = {
    "about", "above", "across", "after", "against",
    "along", "among", "around", "at", "before",
    "behind", "below", "beneath", "beside", "between",
    "by", "concerning", "down", "during", "except",
    "for", "from", "in", "inside", "into",
    "like", "near", "of", "onto", "out",
    "over", "through", "to", "toward", "under",
    "up", "upon", "with", "within", "without"
};

String[] errorpreps = {
    "will", "would", "shall", "should", "can",
    "could", "may", "might", "must", 
};

String[] question = {
};

public static void main(String[] args) {

    generatecode("hi");

};

public generatecode(String code){

    String prep = "";

    for (int i=0; i<preps.length; i++){

        prep = prep + preps[i];

    }

    System.out.println(prep);

    return prep;

}

public String printcode(String code){


    return "";

}

    }

Answer 1

Your method has the wrong access modifier:

public generatecode(String code){

Should be

public static String generatecode(String code){

You didn't have a return type for the method either, so this really shouldn't compile.

Well, static methods like main(String[] args) are capable of being ran, when there is no object instance. So you can call:

ClassName.method();

When you attempt to call an instance method from a static method, this means that you're trying to use code functionality that requires an object instance to exist. So just to recap:

ClassName c = new ClassName();
c.instanceMethod(); // This is an instance method.

ClassName.staticMethod(); // This is a static method.

Answer 2

In your static main method, you don't have any instances of your TestFile class yet. To reference anything that is non- static , you need an instance of the class. That is exactly what the line TestFile variable = new TestFile(); does -- it creates a new instance of TestFile .

Then you can call your method on your instance:

variable.generatecode("hi");

As @ChrisCooney has already pointed out, you don't have a return type for that method. All methods need a return type. In this case, you need to declare that your method returns a String , because that's what the method does return.

Answer 3

generate is an instance method, and you're trying to invoke it from main , which is a static method. To workaround it, you could do.-

(new TestFile()).generatecode("hi");