小编Abd*_*dan的帖子

我刚刚下载了Android Studio.在尝试运行它时,我不得不修改环境变量并添加

JAVA_HOME

和

C:\ PROGRA〜2 \的Java\jdk1.6.0_22

一旦我完成了这个障碍,现在我收到了另一个错误:

The environment variable JAVA_HOME (with the value of *C:\Progra~2\Java\jdk1.6.0_22*) does not point to a valid JVM installation.

我查看了其他类似的问题,我被要求检查版本,所以我在CMD中做了以下事情:

C:\Users\Andre>java -version
java version "1.6.0_22"
Java(TM) SE Runtime Environment (build 1.6.0_22-b04)
Java HotSpot(TM) Client VM (build 17.1-b03, mixed mode, sharing)

C:\Users\Andre>javac -version
javac 1.6.0_22

从结果看来我似乎有JVM.

我也为JAVA_HOME尝试了这些路径,每次关闭并重新打开一个新的CMD窗口

C:\Program Files (x86)\Java\jre7
C:\Program Files (x86)\Java\jre6
C:\Program Files (x86)\Java\jdk1.6.0_22
C:\Program Files (x86)\Java\jre7\bin
C:\Program Files (x86)\Java\jre6\bin
C:\Program Files (x86)\Java\jdk1.6.0_22\bin

我试图弄清楚这个算法是否是A*(A-Star)算法或其他什么,但我仍然感到困惑.

Stack<Cell> stack = new Stack<>();

stack.push(maze.start());
stack.peek().mark(SOLUTION_MARK);

while (!stack.peek().hasMark(Cell.END)) {

    Cell current = stack.peek();
    ArrayList<Cell> dirs = current.neighbors();

    boolean found = false;
    for (Cell next : dirs) {
        if (next.hasMark(ERROR_MARK) || next.hasMark(SOLUTION_MARK)) {
            continue;
        }
        stack.push(next);
        next.mark(SOLUTION_MARK);
        found = true;
        break;
    }
    if (!found) {
        stack.pop().mark(ERROR_MARK);
    }
    for (MazeBody listener : listeners) {
        listener.repaint();
    }
}

Mark.java

public final class Mark {

    private static Map<String, Mark> TABLE = new HashMap<>();

    private String name;

    private Mark(String markName) {
        name = …

我想检查表中是否username已经存在database.

Java代码:

if (e.getSource() == jButton2)
{
  U = jTextField1.getText();
  if (jTextField1.getText().trim().equals(""))
  {
    JOptionPane.showMessageDialog(this, "Please Write Username !");
  } 
  else if (jPasswordField1.getText().equals(""))
  {
    JOptionPane.showMessageDialog(this, "Please Write Password !");
  } 
  else
  {
    try {
      String Driver = "com.mysql.jdbc.Driver"; 
      String URL = "jdbc:mysql://localhost:3306/LoginForm"; 
      Class.forName(Driver); 
      Connection Conn = DriverManager.getConnection(URL, "root", "12345");
      Statement S = Conn.createStatement();
      ResultSet RS = S.executeQuery(
          "SELECT * FROM login where username ='" + U + 
          "' and Password ='" + jPasswordField1.getText() + "'");

      while (RS.next()) …

我想在VB中创建一个包含多种表单的程序,我需要创建一个打开另一个表单的按钮.

form2.open()