写一段java 银行家算法

银行家算法是一种操作系统中用来避免死锁的算法，可以用Java语言实现。下面是一个简单的银行家算法实现示例：

import java.util.*;

public class BankerAlgorithm {
    private int numOfProcesses; // 进程数量
    private int numOfResources; // 资源数量
    private int[] available; // 可用资源数
    private int[][] maximum; // 最大需求矩阵
    private int[][] allocation; // 已分配矩阵
    private int[][] need; // 还需矩阵

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

        for (int i = 0; i < numOfProcesses; i++) {
            for (int j = 0; j < numOfResources; j++) {
                need[i][j] = maximum[i][j] - allocation[i][j];
            }
        }
    }

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

        // 找到一个可行序列
        int count = 0;
        while (count < numOfProcesses) {
            boolean found = false;
            for (int i = 0; i < numOfProcesses; i++) {
                if (!finish[i]) {
                    int j;
                    for (j = 0; j < numOfResources; j++) {
                        if (need[i][j] > work[j]) {
                            break;
                        }
                    }
                    if (j == numOfResources) {
                        for (int k = 0; k < numOfResources; k++) {
                            work[k] += allocation[i][k];
                        }
                        finish[i] = true;
                        found = true;
                        count++;
                    }
                }
            }
            if (!found) {
                break;
            }
        }
        return count == numOfProcesses;
    }

    public boolean requestResources(int pid, int[] request) {
        for (int i = 0; i < numOfResources; i++) {
            if (request[i] > need[pid][i] || request[i] > available[i]) {
                return false;
            }
        }
        for (int i = 0; i < numOfResources; i++) {
            available[i] -= request[i];
            allocation[pid][i] += request[i];
            need[pid][i] -= request[i];
        }
        if (isSafe()) {
            return true;
        } else {
            for (int i = 0; i < numOfResources; i++) {
                available[i] += request[i];
                allocation[pid][i] -= request[i];
                need[pid][i] += request[i];
            }
            return false;
        }
    }
}

这是一个简单的银行家算法实现，可以创建一个BankerAlgorithm对象来进行使用。其中，构造方法接收可用资源数、最大需求矩阵和已分配矩阵作为参数，isSafe方法用于判断当前状态是否安全，requestResources方法用于请求资源并判断请求是否合法。