java Bank 10 3 5 6 2 来执行
public class Bank{
public static void main(String[] args){
// first decide on the capital and the line credits,
// then
// read from the user client id and what he wishes
// if it leads to a safe state grant it, otherwise not.
Banker b;
int clients, capital;
try {
// requires start capital and number of clients.
capital = Integer.parseInt(args[0]);
clients = Integer.parseInt(args[1]);
b= new Banker(capital,clients);
// start the credit lines
for(int i =0; i<clients;i++){
b.startCreditLine(Integer.parseInt(args[i+2]),i);
b.show();
}
}catch (NumberFormatException e) {}
}
}
======================================
import java.awt.*;
import java.awt.event.*;
public class Banker extends Frame{
int capital, available, clients, currentClient;
int[] max, granted, need;
public Banker(int startCapital, int numClients){
capital = startCapital;
available = capital;
clients = numClients;
currentClient=-1;
max = new int[clients];
granted = new int[clients];
need = new int[clients];
for(int i = 0; i<clients;i++){
max=0;
granted=0;
need=0;
}
setUp();
}
public void startCreditLine(int x, int client){
max[client]=x;
need[client]=x;
}
private boolean safe(){
boolean[] finished = new boolean[clients];
int workingCapital = available;
int candidate = 0;
// if what he asked for is enough for him to be satisfied,
// we can just wait for him to finish and return what he has
// so it is safe.
if(need[currentClient]==0) return true;
if(need[currentClient]<0){
System.out.println("The banker cannot give you more than what remains for your max");
return false;
}
if (workingCapital<0){
System.out.println("The banker cannot give you more than what he has available");
return false;
}
for(int i = 0; i<clients; i++)
finished=false;
candidate = nextCandidate(finished,workingCapital);
while (candidate<clients){
// a candidate we can treat!
// he can finish and we can get back what he had.
finished[candidate]=true;
workingCapital = workingCapital + need[candidate];
candidate=nextCandidate(finished,workingCapital);
}
return (allSatisfied(finished));
}
private int nextCandidate(boolean[] f, int wc){
for(int i = 0; i<f.length; i++){
if (f==false && need<=wc){
return i;
}
}
return f.length;
}
private boolean allSatisfied(boolean[] f){
for(int i=0; i<f.length; i++)
if (!f) return false;
return true;
}
private void grant(int x, int client){
granted[client]=granted[client]+x;
available = available -x;
need[client]=need[client]-x;
}
private void setUp(){
TextField client, credit;
Label cl,cr;
Panel p,q;
client=new TextField(10);
credit= new TextField(10);
cl = new Label("Client : ");
cr = new Label("Requires: ");
p=new Panel();
q=new Panel();
p.add(cl);
p.add(client);
q.add(cr);
q.add(credit);
add("North",p);
add("South",q);
pack();
client.addActionListener(new ClientListener());
credit.addActionListener(new CreditListener());
}
private class ClientListener implements ActionListener{
public void actionPerformed(ActionEvent e){
try{
currentClient = Integer.parseInt(e.getActionCommand());
System.out.println("client : "+currentClient);
System.out.println("max : "+max[currentClient]);
System.out.println("granted : "+granted[currentClient]);
System.out.println("need : "+need[currentClient]);
System.out.println("available : "+available);
}catch (NumberFormatException ne) {}
}
}
private class CreditListener implements ActionListener{
public void actionPerformed(ActionEvent e){
int ammount;
try{
ammount = Integer.parseInt(e.getActionCommand());
grant(ammount,currentClient);
if (!safe()){
grant(-ammount,currentClient);
System.out.println("not granted "+ ammount);
System.out.println("available : "+available);
}
else{
System.out.println("granted " + ammount + " to client " + currentClient);
System.out.println("available : "+available);
}
}catch (NumberFormatException ne) {}
}
}
}
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