用java写一个银行家算法

银行家算法是一种避免死锁的算法，它可以确保系统中的资源分配是安全的。以下是一个用 Java 实现银行家算法的示例代码：

import java.util.*;

public class BankerAlgorithm {
    private int[][] need;
    private int[][] allocation;
    private int[] available;
    private int[] safeSequence;
    private int numOfProcesses;
    private int numOfResources;

    public BankerAlgorithm(int[][] need, int[][] allocation, int[] available) {
        this.need = need;
        this.allocation = allocation;
        this.available = available;
        this.numOfProcesses = need.length;
        this.numOfResources = available.length;
        this.safeSequence = new int[numOfProcesses];
    }

    public boolean isSafe() {
        boolean[] finish = new boolean[numOfProcesses];
        int[] work = Arrays.copyOf(available, numOfResources);
        int count = 0;

        while (count < numOfProcesses) {
            boolean found = false;
            for (int i = 0; i < numOfProcesses; i++) {
                if (!finish[i] && Arrays.equals(need[i], Arrays.copyOfRange(work, 0, numOfResources))) {
                    finish[i] = true;
                    work = addArrays(work, allocation[i]);
                    safeSequence[count] = i;
                    count++;
                    found = true;
                }
            }
            if (!found) {
                return false;
            }
        }
        return true;
    }

    public int[] getSafeSequence() {
        if (isSafe()) {
            return safeSequence;
        } else {
            return null;
        }
    }

    private int[] addArrays(int[] a, int[] b) {
        int[] result = new int[a.length];
        for (int i = 0; i < a.length; i++) {
            result[i] = a[i] + b[i];
        }
        return result;
    }
}

这个类接受三个参数：need、allocation 和 available。need 和 allocation 都是二维数组，表示每个进程需要和已经分配的资源数量。available 是一个一维数组，表示当前可用的资源数量。isSafe() 方法用于检查当前状态是否安全，getSafeSequence() 方法返回一个安全序列（如果存在）。

注意：这只是一个简单的实现，实际上银行家算法还有很多细节需要考虑，比如资源请求的顺序、死锁检测等。