Java 从文本框获取文本
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Get text from textfield
提问by Ralph Lorenz
I'm making a GUI program. In my first program I have the following code:
我正在制作一个 GUI 程序。在我的第一个程序中，我有以下代码：
double num1;
num1 = Double.parseDouble(guess.getText());
I believe that this code gets the value from the text field and converts it to double.
我相信这段代码从文本字段中获取值并将其转换为双精度值。
How can I get the value and convert it to String or Char?
如何获取值并将其转换为 String 或 Char？
回答by dARKpRINCE
The getText()already returns the text as String.
Btw, be careful of Exceptions due to parse error. But your on the right track. :)
该getText()已返回文本为String。顺便说一句，注意由于解析错误引起的异常。但你在正确的轨道上。:)
回答by Ayvadia
The getText()method returns a String. when you use .parseDoublewhat you are really doing is turning the string the user entered and into a double therefore in the case of a string you do not have to use a .parse method because the value called is already a string. In the case of a character you would have to use something like this:
该getText()方法返回一个字符串。当您使用.parseDouble您真正在做的事情时，将用户输入的字符串转换为双精度值，因此在字符串的情况下，您不必使用 .parse 方法，因为调用的值已经是一个字符串。在字符的情况下，您必须使用以下内容：
String text = jTextField1.getText();
if (text.length() > 1 && !text.contains(" ") && !text.contains(",")) {
//make sure that its length is not over 1, and that it has no spaces and no commas
char ch = text;
} else {
//if a space or comma was found no matter how big the text it will execute the else..
System.out.println("this is not allowed");
jTextField1.setText("");
}
回答by afsantos
Since the getText()already returns a String, storing its value as a Stringis trivial.
由于getText()已经返回 a String，将其值存储为 aString是微不足道的。
In order to parse a double, you've already done it, just watch for the NumberFormatException, in case of invalid input.
为了解析 a double，您已经完成了，只需注意NumberFormatException, 以防输入无效。
To store its value as a char, that depends on your requirements. Do you want the first character? Do you require the string to have only a single character? Is any character valid? And so on.
要将其值存储为 a char，这取决于您的要求。你想要第一个字符吗？您是否要求字符串只有一个字符？任何字符都有效吗？等等。
// Storing the value as a String.
String value = guess.getText();
// Storing the value as a double.
double doubleValue;
try {
doubleValue = Double.parseDouble(value);
} catch (NumberFormatException e) {
// Invalid double String.
}
// Storing the value as a char.
char firstChar = value.length() > 0 ? value.charAt(0) : (char) 0;
// Require the String to have exactly one character.
if (value.length() != 1) {
// Error state.
}
char charValue = value.charAt(0);
回答by Vasu Gupta
The getText()function already fetches a Stringvalue from the Textfield.
该getText()函数已经String从Textfield.
For example:
例如：
String var = guess.getText();
Here, varis storing the Stringvalue received from the Textfield.
这里，var是存储String从Textfield.
回答by user8615675
use String.valueOf() instead of Double.parseDouble() this will help you convert double into string value
使用 String.valueOf() 而不是 Double.parseDouble() 这将帮助您将 double 转换为字符串值
