Java StringJoiner

Java在java.util包中添加了一个新的最终类StringJoiner。它用于构造由定界符分隔的字符序列。现在, 你可以通过传递诸如comma（, ）, hyphen（-）等分隔符来创建字符串。还可以将前缀和后缀传递给char序列。

StringJoiner构造函数

StringJoiner方法

Java StringJoiner示例

// importing StringJoiner class
import java.util.StringJoiner;
public class StringJoinerExample {
	public static void main(String[] args) {
		StringJoiner joinNames = new StringJoiner(", ");	// passing comma(, ) as delimiter 
		
		// Adding values to StringJoiner
		joinNames.add("Rahul");
		joinNames.add("Raju");
		joinNames.add("Peter");
		joinNames.add("Raheem");
				
		System.out.println(joinNames);
	}
}

输出：

Rahul, Raju, Peter, Raheem

Java StringJoiner示例：添加前缀和后缀

// importing StringJoiner class
import java.util.StringJoiner;
public class StringJoinerExample {
	public static void main(String[] args) {
		StringJoiner joinNames = new StringJoiner(", ", "[", "]");	// passing comma(, ) and square-brackets as delimiter 
		
		// Adding values to StringJoiner
		joinNames.add("Rahul");
		joinNames.add("Raju");
		joinNames.add("Peter");
		joinNames.add("Raheem");
				
		System.out.println(joinNames);
	}
}

输出：

[Rahul, Raju, Peter, Raheem]

StringJoiner示例：合并两个StringJoiner

merge()方法合并两个StringJoiner对象, 但不包括第二个StringJoiner对象的前缀和后缀。

// importing StringJoiner class
import java.util.StringJoiner;
public class StringJoinerExample {
	public static void main(String[] args) {

		StringJoiner joinNames = new StringJoiner(", ", "[", "]");	// passing comma(, ) and square-brackets as delimiter 
		
		// Adding values to StringJoiner
		joinNames.add("Rahul");
		joinNames.add("Raju");

		// Creating StringJoiner with :(colon) delimiter
		StringJoiner joinNames2 = new StringJoiner(":", "[", "]");	// passing colon(:) and square-brackets as delimiter 
		
		// Adding values to StringJoiner
		joinNames2.add("Peter");
		joinNames2.add("Raheem");

		// Merging two StringJoiner
		StringJoiner merge = joinNames.merge(joinNames2); 
		System.out.println(merge);
	}
}

输出：

[Rahul, Raju, Peter:Raheem]

StringJoiner示例：StringJoiner方法

// importing StringJoiner class
import java.util.StringJoiner;
public class StringJoinerExample {
	public static void main(String[] args) {
		StringJoiner joinNames = new StringJoiner(", ");	// passing comma(, ) as delimiter 
		
		// Prints nothing because it is empty
		System.out.println(joinNames);
		
		// We can set default empty value.
		joinNames.setEmptyValue("It is empty");
		System.out.println(joinNames);
		
		
		// Adding values to StringJoiner
		joinNames.add("Rahul");
		joinNames.add("Raju");
		System.out.println(joinNames);
		
		// Returns length of StringJoiner
		int length = joinNames.length();
		System.out.println("Length: "+length);
		
		// Returns StringJoiner as String type 
		String str = joinNames.toString();
		System.out.println(str);
		
		// Now, we can apply String methods on it
		char ch = str.charAt(3);
		System.out.println("Character at index 3: "+ch);
		
		// Adding one more element 
		joinNames.add("Sorabh");
		System.out.println(joinNames);
		
		// Returns length
		int newLength = joinNames.length();
		System.out.println("New Length: "+newLength);
	}
}

输出：

It is empty
Rahul, Raju
Length: 10
Rahul, Raju
Character at index 3: u
Rahul, Raju, Sorabh
New Length: 17