What is the method in Java to remove white spaces from a string?

In Java, you can use the following method to remove spaces from a string:

1. remove extra spaces from both the beginning and end of a string

String str = "  hello world  ";
String trimmedStr = str.trim();
System.out.println(trimmedStr); // 输出: "hello world"

1. Replace all occurrences.

String str = "  hello world  ";
String noSpaceStr = str.replaceAll("\\s", "");
System.out.println(noSpaceStr); // 输出: "helloworld"

1. substitute

String str = "  hello world  ";
String noSpaceStr = str.replace(" ", "");
System.out.println(noSpaceStr); // 输出: "helloworld"

These methods can be selected based on specific needs to choose which way to remove spaces.