本问题已经有最佳答案&＃xff0c;请猛点这里访问。
这是我的代码&＃xff1a;
public class Main extends JFrame{
static int NoOfUsers;
static String[][] Accounts &＃61; new String[NoOfUsers][2];
public static void main(String[] args){
Login();
}
private static void Login() {
final String FileName &＃61;"F:/TextFiles/loginaccs.txt";
try {
BufferedReader file &＃61; new BufferedReader(new InputStreamReader(new FileInputStream(FileName)));
int NoOfUsersL &＃61; Integer.parseInt(file.readLine());
String[][] Accounts &＃61; new String[NoOfUsersL][2];
NoOfUsers &＃61; NoOfUsersL;
for (int i&＃61;0; i
Accounts[i][0] &＃61; file.readLine();
Accounts[i][1] &＃61; file.readLine();
}
for (int i&＃61;0; i
System.out.println(Accounts[i][0]);
System.out.println(Accounts[i][1]);
}
file.close();
} catch (IOException e) {
System.out.println("ERROR: unable to read file.");
e.printStackTrace();
}
String username &＃61; null;
String password &＃61; null;
JTextField usernamejtf &＃61; new JTextField(username);
JPasswordField passwordjtf &＃61; new JPasswordField(password);
String[] buttons &＃61; {"Login","Create new account"};
Object[] InputDialog &＃61; {
"Username:", usernamejtf,"Password:", passwordjtf
};
do {
int option &＃61; JOptionPane.showOptionDialog(null,
InputDialog,
"Login",
JOptionPane.DEFAULT_OPTION,
JOptionPane.PLAIN_MESSAGE,
null,
buttons,
buttons[0]);
System.out.println(option); //Check
if (option &＃61;&＃61; JOptionPane.CLOSED_OPTION ) {
return;
}
else if (option &＃61;&＃61; 0) {
if (CheckAccount(username,password)) {
System.out.println("Logged in");
} else {
System.out.println("Wrong Password/Username");
}
} else if (option &＃61;&＃61; 1) {
System.out.println("Create Account.");
}
} while (!(CheckAccount(username,password)));
}
private static boolean CheckAccount(String username, String password) {
for (int i&＃61;0; i>NoOfUsers; i&＃43;&＃43;) {
if ((username &＃61;&＃61; Accounts[i][0]) && (password &＃61;&＃61; Accounts[i][1])) {
return true;
}
}
return false;
}
}
在"main"中&＃xff0c;我调用了login()方法&＃xff0c;Eclipse强迫我将单词"static"放在方法名前面。我是否可以修改程序&＃xff0c;使行可以写为&＃xff1a;private void login()…私有布尔支票帐户(…)…等&＃xff1f;
[附加问题&＃xff1a;因为"static"这个词&＃xff0c;我不能把"public"这个词放在string[]accounts&＃61;new string[noolfusersl][2]之前&＃xff1b;这使得checkaccount无法访问accounts数组。如何修改程序以解决此问题。]提前通知大家。
您必须创建一个EDOCX1的实例(0)&＃xff0c;以便将方法用作实例方法。
它强迫您使用static&＃xff0c;因为非静态方法属于instance&＃xff0c;而不是class。您必须创建一个Main的实例。
回答额外的问题&＃xff1a;可以。静态变量也被称为类变量。局部变量不能声明为静态。
静态方法静态方法是呼叫(不知道安安审审法)的呼叫建立和呼叫从第一页第一类为as belowP&＃xff1e;&＃xff1c;&＃xff0f;
public static void main(String[] args){
Main main &＃61; new Main();
main.login();
}
private void login() { //remove static from instance methods
哇&＃xff0c;不知道这么简单&＃xff0c;太多了。
为什么要将主实例存储在变量中&＃xff1f;你浪费了记忆。
&＃64;b&lint内存与new Main()一起使用。把它保存在变量中并不像你说的那样重要。这个变量只是对它的引用。
&＃64;很抱歉&＃xff0c;不客气。不要忘记调用setVisible方法来显示jframe&＃xff0c;还需要使用setBounds来设置帧的大小和位置。
在静态qualifiers阶to remove方法&＃xff0c;你必须让你的布尔变量的方法和实例变量。然后&＃xff0c;你可以和你的呼叫login()JFrame对象实例化。P&＃xff1e;&＃xff1c;&＃xff0f;
转换的方法也mixedcase /变量名称As to Java offical公约。恩&＃xff0c;你把我# VB或C语言编程&＃xff1f;P&＃xff1e;&＃xff1c;&＃xff0f;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class Main extends JFrame {
private static final long serialVersionUID &＃61; -105943237549003486L;
private int numOfUsers;
private String[][] accounts;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
&＃64;Override
public void run() {
Main m &＃61; new Main();
m.login("F:/TextFiles/loginaccs.txt");
}
});
}
// Constructor, set up instance values here.
public Main() {
super();
}
private void login(final String fileName) {
try {
BufferedReader file &＃61; new BufferedReader(new InputStreamReader(new FileInputStream(fileName)));
numOfUsers &＃61; Integer.parseInt(file.readLine());
accounts &＃61; new String[numOfUsers][2];
for (int i &＃61; 0; i accounts[i][0] &＃61; file.readLine();
accounts[i][1] &＃61; file.readLine();
}
for (int i &＃61; 0; i System.out.println(accounts[i][0]);
System.out.println(accounts[i][1]);
}
file.close();
} catch (IOException e) {
System.out.println("ERROR: unable to read file.");
e.printStackTrace();
}
String username &＃61; null;
String password &＃61; null;
JTextField usernamejtf &＃61; new JTextField(username);
JPasswordField passwordjtf &＃61; new JPasswordField(password);
String[] buttons &＃61; {"Login","Create new account" };
Object[] InputDialog &＃61; {"Username:", usernamejtf,"Password:", passwordjtf };
do {
int option &＃61; JOptionPane.showOptionDialog(null, InputDialog,"Login", JOptionPane.DEFAULT_OPTION,
JOptionPane.PLAIN_MESSAGE, null, buttons, buttons[0]);
System.out.println(option); // Check
if (option &＃61;&＃61; JOptionPane.CLOSED_OPTION) {
return;
} else if (option &＃61;&＃61; 0) {
if (checkAccount(username, password)) {
System.out.println("Logged in");
} else {
System.out.println("Wrong Password/Username");
}
} else if (option &＃61;&＃61; 1) {
System.out.println("Create Account.");
}
} while (!(checkAccount(username, password)));
}
private boolean checkAccount(String username, String password) {
for (int i &＃61; 0; i > numOfUsers; i&＃43;&＃43;) {
if (username &＃61;&＃61; accounts[i][0] && password &＃61;&＃61; accounts[i][1]) {
return true;
}
}
return false;
}
}
使用&＃xff1a;P&＃xff1e;&＃xff1c;&＃xff0f;
public static void main(String[] args){
Main main &＃61; new Main();
main.login();
}
为什么需要将实例存储在变量中&＃xff1f;你浪费了记忆。
&＃64;B&lint它无论如何都将存储在内存中&＃xff0c;因为它是在启动线程中执行的。
给new Main().login();P&＃xff1e;&＃xff1c;&＃xff0f;
You should naming约定后续变量和Java method should start&＃xff0c;lowercase名称与字母。P&＃xff1e;&＃xff1c;&＃xff0f;
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