java 将空字符串转换为“”
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Convert null string to ""
提问by dwjohnston
If I have
如果我有
String a = null;
System.out.println(a);
I'll get
我去拿
null
null
Is there an elegant way to change this an empty string?
有没有一种优雅的方法来改变这个空字符串？
I could do:
我可以做：
if (a == null){
a="";
}
The context is that I'll be producing a string of the form:
上下文是我将生成以下形式的字符串：
String myString = a + "\n" + b + "\n" + c;
String myString = a + "\n" + b + "\n" + c;
But I'm wondering if there's a nicer solution.
但我想知道是否有更好的解决方案。
回答by shauryachats
You could try it like this using the ternary operator.
您可以像这样使用三元运算符尝试它。
System.out.println(a == null ? "" : a);
Alernatively, you can use the Commons Lang3 function defaultString()as suggested by chrylis,
或者，您可以使用 chrylisdefaultString()建议的 Commons Lang3 函数，
System.out.println(StringUtils.defaultString(a));
回答by Bohemian
I would factor out a utility method that captures the intention, which improves readability and allows easy reuse:
我会提取出一种捕获意图的实用方法，它提高了可读性并允许轻松重用：
public static String blankIfNull(String s) {
return s == null ? "" : s;
}
Then use that when needed:
然后在需要时使用它：
System.out.println(blankIfNull(a));
回答by dwjohnston
Apache commons lang3has a function that will do this.
Apache commons lang3有一个功能可以做到这一点。
import org.apache.commons.lang3.StringUtils;
a = null;
System.out.println(StringUtils.defaultString(a));
回答by Paul Boddington
You could write a varargs method
你可以写一个可变参数方法
public static String concat(String... arr) {
StringBuilder sb = new StringBuilder();
for (String s : arr)
if (s != null)
sb.append(s);
return sb.toString();
}
Then you can do
然后你可以做
String myString = concat(a, "\n", b, "\n", c);
