public int exchange(int a,int b,int c) { c = b; a = b; return a, b; }

这段代码中有一个错误，返回值应该是两个整数而不是一个。此外，变量c没有被使用，所以赋值c=b没有意义。正确的实现应该是：

public void exchange(int a, int b) {
int temp = a;
a = b;
b = temp;
}

这个方法不需要返回值，因为它直接修改了传入的参数a和b的值。

相关问题

我想要返回a，b两个值要怎么办哇

你可以将这两个值封装到一个数组中，然后将数组作为返回值。例如：

public int[] exchange(int a, int b) {
int temp = a;
a = b;
b = temp;
return new int[]{a, b};
}

这样，调用exchange方法可以得到交换后的a和b的值：

int a = 1;
int b = 2;
int[] result = exchange(a, b);
a = result[0];
b = result[1];
System.out.println("a=" + a + ", b=" + b); // 输出 a=2, b=1

#include<iostream> #include<cmath> #include<algorithm> using namespace std; struct point { int x, y, index; double theta; } p[30000], temp; int f(point& a, point& b) { if (a.theta == b.theta) { if (a.x == b.x && a.y > 0) return a.y * a.y > b.y * b.y; else return a.x * a.x + a.y * a.y < b.x* b.x + b.y * b.y; }return a.theta < b.theta; }int main() { int n; cin >> n; //input for (int i = 0; i < n; i++) { int x, y; cin >> p[i].x >> p[i].y; p[i].index = i + 1; }//exchange min_x to first position int min = p[0].x, minPosition = 0; for (int i = 1; i < n; i++) { minPosition = min <= p[i].x ? minPosition : i; min = min <= p[i].x ? min : p[i].x; }temp = p[0]; p[0] = p[minPosition]; p[minPosition] = temp; //cal atan2 for (int i = 1; i < n; i++) { p[i].x -= p[0].x; p[i].y -= p[0].y; p[i].theta = atan2(p[i].y, p[i].x); }//sort exclude min_x sort(p + 1, p + n, f); //output cout << n << endl; for (int i = 0; i < n; i++) { if (p[i].index == 1) { for (int j = i; j < n; j++) cout << p[j].index << endl; for (int j = 0; j < i; j++) cout << p[j].index << endl; break; } } }转为Java

以下是将给定的 C++ 代码转换为 Java 代码的结果：

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {
    static class Point {
        int x, y, index;
        double theta;

        public Point(int x, int y, int index, double theta) {
            this.x = x;
            this.y = y;
            this.index = index;
            this.theta = theta;
        }
    }

    static Point[] p = new Point[30000];

    static int f(Point a, Point b) {
        if (a.theta == b.theta) {
            if (a.x == b.x && a.y > 0)
                return a.y * a.y > b.y * b.y ? 1 : -1;
            else
                return a.x * a.x + a.y * a.y < b.x * b.x + b.y * b.y ? 1 : -1;
        }
        return a.theta < b.theta ? 1 : -1;
    }

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();

        // input
        for (int i = 0; i < n; i++) {
            int x = scan.nextInt();
            int y = scan.nextInt();
            p[i] = new Point(x, y, i + 1, 0);
        }

        // exchange min_x to first position
        int min = p[0].x, minPosition = 0;
        for (int i = 1; i < n; i++) {
            minPosition = min <= p[i].x ? minPosition : i;
            min = min <= p[i].x ? min : p[i].x;
        }
        Point temp = p[0];
        p[0] = p[minPosition];
        p[minPosition] = temp;

        // cal atan2
        for (int i = 1; i < n; i++) {
            p[i].x -= p[0].x;
            p[i].y -= p[0].y;
            p[i].theta = Math.atan2(p[i].y, p[i].x);
        }

        // sort exclude min_x
        Arrays.sort(p, 1, n, new Comparator<Point>() {
            @Override
            public int compare(Point a, Point b) {
                return f(a, b);
            }
        });

        // output
        System.out.println(n);
        for (int i = 0; i < n; i++) {
            if (p[i].index == 1) {
                for (int j = i; j < n; j++)
                    System.out.println(p[j].index);
                for (int j = 0; j < i; j++)
                    System.out.println(p[j].index);
                break;
            }
        }

        scan.close();
    }
}