Question

我已经尝试了所有事情，我仍然无法使这个代码正常运行

public void Action(ActionEvent event)
{
    //We get the text from the textfield
    String fromUser = textfield1.getText();

    if (fromUser != null) {
        if(x<1)
        {
            if(fromUser.length() <= 10)
            {                                
                USERNAME = fromUser;
                x++;
                textfield1.setText("");
            }
            else
            {
                textarea1.setText("Username Surpasses Size Limit Please Try Again\nUsername Must Be 10 Characters Or Less");
                textfield1.setText("");
            }
        }
        else
        {
            if(x==1)
            {
                textarea1.setText("");
                x++;
            }
            //We append the text from the user
            textarea1.append(USERNAME+"> " + fromUser + "\n");
            //The pane auto-scrolls with each new response added
            textarea1.setCaretPosition(textarea1.getDocument().getLength());
            //We reset our text field to "" each time the user presses Enter
            textfield1.setText("");

            //This is Where my code should work
            if(fromUser == "n")
            {
                InitiateText("North");
            }
            else if(fromUser == "s")
            {
                InitiateText("South");
            }
            else if(fromUser == "w")
            {
                InitiateText("West");
            }
            else if(fromUser == "e")
            {
                InitiateText("East");
            }
            else
            {
                InitiateText("I don't comprehend");
            }
        }
    }
}   

public void InitiateText(String Where) //Where are you on the map
{
    //We append the text from the user
    textarea1.append("Map > " + Where + "\n");
    //The pane auto-scrolls with each new response added
    textarea1.setCaretPosition(textarea1.getDocument().getLength());
    //We reset our text field to "" each time the user presses Enter
    textfield1.setText("");
}

这是我最近尝试做的事情，添加文字的方法工作正常，但if语句不起作用，我输入＆＃34; n＆＃34;并且它不会识别＆＃34; n＆＃34;我输入了。我做错了什么？

Answer 1

将if(fromUser == "n")更改为if(fromUser.equals("n"))并使用equals()方法而不是==更改每个语句以比较字符串。

==运算符只是检查引用是否引用相同的字符串对象，它们不检查String的相等性。阅读String comparison with equals and assignment operator

如何使用来自JTextFields的If语句

1 个答案: