Question

我写了一些代码，只是想知道是否有更简洁的方法来做以防万一我必须做额外的条件？我不想使用嵌套的ifs。

有没有办法让它更加面向对象？

  if(!usernameExists)
  {
      if(!username.matches("^[\\pL\\pN]+$") || 
          username.length() < 7 || 
          username.length() > 25)
      {
          usernameValid=false;
          Forms.Main.instructorForm.usernameField.setBackground(Color.red);
          Forms.Main.instructorForm.usernameField.setToolTipText(
             "<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>");
      }
      else
      {
          Forms.Main.instructorForm.usernameField.setBackground(Color.white);
          Forms.Main.instructorForm.usernameField.setToolTipText("");
      }
  }
  else
  {
      usernameValid=false;
      Forms.Main.instructorForm.usernameField.setBackground(Color.red);
      Forms.Main.instructorForm.usernameField.setToolTipText(
          "This username already exists!");
  }

Answer 1

我没有假设你所呈现的逻辑的正确性，但是对于我所显示的内容，我建议你重构并将第一个布尔值提取到一个单独的方法中。

if(!usernameExists) {
    usernameValid = validateUsernameAndSetBackground(username);
} else {
    // rest of code
}


public boolean validateUsernameAndSetBackground(String username) {
    boolean result = true;
    if(!username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25) {
        result = false;
        Forms.Main.instructorForm.usernameField.setBackground(Color.red);
        Forms.Main.instructorForm.usernameField.setToolTipText("<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>");
    } else {
        Forms.Main.instructorForm.usernameField.setBackground(Color.white);
        Forms.Main.instructorForm.usernameField.setToolTipText("");
    }
    return result;
}

还有其他重构机会 - 即背景颜色和字段的设置。但这解决了很多条件性条款深层嵌套的直接问题。

Answer 2

我要做的是以下内容。这摆脱了一些神奇的数字并稍微分散了责任。

public static final String USERNAME_KEY = "^[\\pL\\pN]+$";
public static final int USERNAME_MIN_LENGTH = 7;
public static final int USERNAME_MAX_LENGTH = 25;

void foo() {
    if(!usernameExists) {
        usernameValid = validateUsernameAndSetBackground(username);
    } else {
        usernameValid = false;
        adjustFormSettings(Color.red, "This username already exists!");
    }
}


private boolean validateUsernameAndSetBackground(String username) {
    if(usernameIsValid(username)) {
        adjustFormSettings(Color.white, "");
        return true;
    } else {
        adjustFormSettings(Color.red, getInvalidUsernameErrorMsg());
        return false;
    }
}

private void adjustFormSettings(Color color, String msg) {
    Forms.Main.instructorForm.usernameField.setBackground(Color.red);
    Forms.Main.instructorForm.usernameField.setToolTipText(getErrorMsg());
}

private boolean usernameIsValid(String username) {
    return username.matches(USERNAME_KEY) 
     && username.length() >= USERNAME_MIN_LENGTH 
     && username.length() <= USERNAME_MAX_LENGTH;
}

private String getInvalidUsernameErrorMsg() {
    return "<html>Only letters & numbers allowed!<br> Length must be between "
     + USERNAME_MIN_LENGTH + " and " + USERNAME_MAX_LENGTH + ".</html>";
}

Answer 3

我会按如下方式重新格式化您的示例。（注意我使用不常见的缩进来关闭'}'）：

if(usernameExists) {
    usernameValid=false;
    Forms.Main.instructorForm.usernameField.setBackground(Color.red);
    Forms.Main.instructorForm.usernameField.setToolTipText("This username already exists!");
    }
else if(!username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25) {
    usernameValid=false;
    Forms.Main.instructorForm.usernameField.setBackground(Color.red);
    Forms.Main.instructorForm.usernameField.setToolTipText("<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>");
    }
else if(/* other validation conditions here...*/) {
    }
else {
    Forms.Main.instructorForm.usernameField.setBackground(Color.white);
    Forms.Main.instructorForm.usernameField.setToolTipText("");
    }

Answer 4

第一步：使用默认值。

usernameValid=false;
Forms.Main.instructorForm.usernameField.setBackground(Color.red);
Forms.Main.instructorForm.usernameField.setToolTipText("This username already exists!");

if (!usernameExists) {
    usernameValid=true;
    Forms.Main.instructorForm.usernameField.setBackground(Color.white);
    Forms.Main.instructorForm.usernameField.setToolTipText("");

    if(!username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25) {
        usernameValid=false;
        Forms.Main.instructorForm.usernameField.setBackground(Color.red);
        Forms.Main.instructorForm.usernameField.setToolTipText("<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>");
    }
}

第二步：消除冗余信息

Forms.Main.instructorForm.usernameField.setToolTipText("This username already exists!");

if (!usernameExists) {
    Forms.Main.instructorForm.usernameField.setToolTipText("");

    if(!username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25) {
        Forms.Main.instructorForm.usernameField.setToolTipText("<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>");
    }
}

boolean usernameValid = Forms.Main.instructorForm.usernameField.getToolTipText().length() > 0);
Forms.Main.instructorForm.usernameField.setBackground(usernameValid ? Color.white : Color.red);

第三步：替换技术信息

String error = "This username already exists!";

if (!usernameExists) {
    error = "";

    if(!username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25) {
        error = "<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>";
    }
}

Forms.Main.instructorForm.usernameField.setToolTipText(error);
boolean usernameValid = error.length() > 0;
Forms.Main.instructorForm.usernameField.setBackground(usernameValid ? Color.white : Color.red);

第四步：减少巢穴

String error = usernameExists ? "This username already exists!" : "";

if("".equals(error) && (!username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25)) {
    error = "<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>";
}

Forms.Main.instructorForm.usernameField.setToolTipText(error);
boolean usernameValid = "".equals(error) == false;
Forms.Main.instructorForm.usernameField.setBackground(usernameValid ? Color.white : Color.red);

第五步：制定更有意义的方法

boolean isUsernameValid(String username) {
    return !username.matches("^[\\pL\\pN]+$") || username.length() < 7 || username.length() > 25);
}

boolean noErrors(error) {
    return "".equals(error);
}

String error = usernameExists ? "This username already exists!" : "";

if(noErrors(error) && isUsernameValid(username) == false) {
    error = "<html>Only letters & numbers allowed!<br> Length must be between 6 and 26</html>";
}

boolean usernameValid = noErrors(error);
Forms.Main.instructorForm.usernameField.setToolTipText(error);
Forms.Main.instructorForm.usernameField.setBackground(usernameValid ? Color.white : Color.red);

Java嵌套Ifs - 可以通过编码最佳实践来解决吗？

4 个答案: