Java代码编译报错：IDENTIFIER EXPECTED/ILLEGAL START OF TYPE求助

Hey there! Let's break down what's going wrong with your code. The root issue here is a fundamental Java syntax rule: you can't put executable statements directly at the top level of a class.

What's Wrong? #

In Java, the direct contents of a class can only be things like:

• Member variable declarations
• Method definitions
• Constructors
• Inner classes/interfaces

Your code is trying to run auto.add(...) calls and a for-loop directly inside the testArrayList class, outside of any method or constructor. The compiler has no idea how to handle these standalone executable lines at the class level, hence the confusing error messages.

Fixed Code Example #

The simplest fix is to wrap your logic inside a main method (the standard entry point for Java programs). I've also adjusted the class name to follow Java's naming conventions (uppercase first letter for classes):

import java.util.ArrayList;

class TestArrayList {
    public static void main(String[] args) {
        ArrayList<String> auto = new ArrayList<String>();
        auto.add("MITSUBISHI");
        auto.add("Hyundae");
        auto.add("Ford");
        auto.add("Ferrari");
        auto.add("Mazda");
        auto.add("Mustang");
        auto.add("Lamborghini");
        
        for(String cars : auto) {
            System.out.println(cars);
        }
    }
}

Alternative: Using a Constructor #

If you want this logic to run whenever an instance of your class is created, you can put it in a constructor instead:

import java.util.ArrayList;

class TestArrayList {
    private ArrayList<String> auto;

    public TestArrayList() {
        auto = new ArrayList<String>();
        auto.add("MITSUBISHI");
        auto.add("Hyundae");
        auto.add("Ford");
        auto.add("Ferrari");
        auto.add("Mazda");
        auto.add("Mustang");
        auto.add("Lamborghini");
        
        for(String cars : auto) {
            System.out.println(cars);
        }
    }

    public static void main(String[] args) {
        new TestArrayList(); // Create an instance to trigger the constructor logic
    }
}

Either of these approaches will resolve the compiler errors by putting your executable code in a valid scope.

内容的提问来源于stack exchange，提问作者sireee