java - 无法对非静态方法 nextInt() 进行静态引用

Question

这个问题已经有答案了:

Cannot make a static reference to the non-static method (8 个回答)

已关闭 5 年前。

我使用Random类生成从1到20的数字。然后，我将其添加到ArrayList中，但错误消息显示“Cannot make a static reference to the non-static method nextInt(int) from the type随机的”。我该怎么办？下面是我的代码。

import java.util.ArrayList;
import java.util.Random;

public class ComputerChoose {

static ArrayList<Integer> computer_number = new ArrayList<>();

public static ArrayList<Integer> getTheNumber() {

    for(int times=0; times<5; times++)
    {
        computer_number.add(Random.nextInt(20) + 1);
    }

    return computer_number;
    }
}

Answer 1

nextInt 不是静态方法。您必须创建Random的实例，并将其作为实例方法调用:

import java.util.ArrayList;
import java.util.Random;

public class ComputerChoose {

    static ArrayList<Integer> computer_number = new ArrayList<>();

    public static ArrayList<Integer> getTheNumber() {
        Random random = new Random();

        for(int times=0; times<5; times++) {
            computer_number.add(random.nextInt(20) + 1);
        }

        return computer_number;
    }
}

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See also the JavaDocs for java.util.Random.