用java写一个银行家算法
时间: 2023-03-21 21:02:54 浏览: 43
银行家算法是一种资源分配算法,它用于避免死锁并确保系统的安全性。以下是用 Java 实现银行家算法的示例代码:
```java
public class BankerAlgorithm {
private int[][] need; // 需求矩阵
private int[][] allocation; // 分配矩阵
private int[] available; // 可用资源向量
private int numOfProcesses; // 进程数
private int numOfResources; // 资源数
// 构造函数
public BankerAlgorithm(int[][] need, int[][] allocation, int[] available) {
this.need = need;
this.allocation = allocation;
this.available = available;
this.numOfProcesses = allocation.length;
this.numOfResources = available.length;
}
// 检查当前状态是否安全
public boolean isSafe() {
boolean[] finish = new boolean[numOfProcesses];
int[] work = new int[numOfResources];
System.arraycopy(available, 0, work, 0, numOfResources);
// 初始化 finish 数组
for (int i = 0; i < numOfProcesses; i++) {
finish[i] = false;
}
// 执行银行家算法
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;
}
// 分配资源
public boolean allocate(int processId, int[] request) {
for (int i = 0; i < numOfResources; i++) {
if (request[i] > need[processId][i] || request[i] > available[i]) {
return false;
}
}
for (int i = 0; i < numOfResources; i++) {
available[i] -= request[i];
allocation[processId][i] += request[i];
need[processId][i] -= request[i];
}
return true;
}
// 释放资源
public void release(int processId, int[] release) {
for (int i = 0; i < numOfResources; i++) {
available[i] += release[i];
allocation[processId][i] -= release[i];
need[processId][i] += release[i];
}
}
}
```
使用示例:
```java
int[][] need = {
{3, 2, 2},
{0, 0, 1},
{3, 0, 3},
{2, 1, 1}
};
int[][] allocation = {
{0, 0, 1},
{3, 0, 0},
{2, 1, 0},
{0, 0, 2}
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