java 返回多个对象

在Java中，返回多个对象可以通过以下几种方式实现：

1. 使用集合类

可以使用List、Set或Map等集合类来封装多个对象。

示例代码：

import java.util.ArrayList;
import java.util.List;

public class MultipleObjectsExample {
    public static List<Object> getMultipleObjects() {
        List<Object> objects = new ArrayList<>();
        objects.add(new String("Hello"));
        objects.add(42);
        objects.add(3.14);
        return objects;
    }

    public static void main(String[] args) {
        List<Object> result = getMultipleObjects();
        for (Object obj : result) {
            System.out.println(obj);
        }
    }
}

2. 使用自定义类

创建一个包含多个属性的自定义类，然后返回该类的实例。

示例代码：

public class MultipleObjectsExample {
    public static class Result {
        private String message;
        private int number;
        private double value;

        public Result(String message, int number, double value) {
            this.message = message;
            this.number = number;
            this.value = value;
        }

        // Getters and setters
        public String getMessage() {
            return message;
        }

        public void setMessage(String message) {
            this.message = message;
        }

        public int getNumber() {
            return number;
        }

        public void setNumber(int number) {
            this.number = number;
        }

        public double getValue() {
            return value;
        }

        public void setValue(double value) {
            this.value = value;
        }
    }

    public static Result getMultipleObjects() {
        return new Result("Hello", 42, 3.14);
    }

    public static void main(String[] args) {
        Result result = getMultipleObjects();
        System.out.println(result.getMessage());
        System.out.println(result.getNumber());
        System.out.println(result.getValue());
    }
}

3. 使用元组（Tuple）

虽然Java标准库中没有内置的元组类型，但可以使用第三方库（如Apache Commons Lang）或自定义元组类。

示例代码（使用自定义元组类）：

public class MultipleObjectsExample {
    public static class Tuple<A, B, C> {
        private final A first;
        private final B second;
        private final C third;

        public Tuple(A first, B second, C third) {
            this.first = first;
            this.second = second;
            this.third = third;
        }

        public A getFirst() {
            return first;
        }

        public B getSecond() {
            return second;
        }

        public C getThird() {
            return third;
        }
    }

    public static Tuple<String, Integer, Double> getMultipleObjects() {
        return new Tuple<>("Hello", 42, 3.14);
    }

    public static void main(String[] args) {
        Tuple<String, Integer, Double> result = getMultipleObjects();
        System.out.println(result.getFirst());
        System.out.println(result.getSecond());
        System.out.println(result.getThird());
    }
}