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📜  Groovy-字符串

📅  最后修改于: 2020-11-04 06:39:29             🧑  作者: Mango

在Groovy中，通过将字符串文本括在引号中来构造String字面量。

Groovy提供了多种表示String字面量。 Groovy中的字符串可以用单引号(’)，双引号(“)或三引号(”“”)括起来。此外，用三引号引起来的Groovy字符串可能会跨越多行。

以下是Groovy中字符串用法的示例-

现场演示
class Example { 
   static void main(String[] args) { 
      String a = 'Hello Single'; 
      String b = "Hello Double"; 
      String c = "'Hello Triple" + "Multiple lines'";
        
      println(a); 
      println(b); 
      println(c); 
   } 
}

当我们运行上面的程序时，我们将得到以下结果-

Hello Single 
Hello Double 
'Hello TripleMultiple lines'

字符串索引

Groovy中的字符串是字符的有序序列。字符串的单个字符可以通过其位置进行访问。这由索引位置给出。

字符串索引从零开始，以小于字符串长度的一结束。 Groovy还允许负索引从字符串的结尾算起。

以下是Groovy中字符串索引用法的示例-

现场演示
class Example { 
   static void main(String[] args) { 
      String sample = "Hello world"; 
      println(sample[4]); // Print the 5 character in the string
        
      //Print the 1st character in the string starting from the back 
      println(sample[-1]); 
      println(sample[1..2]);//Prints a string starting from Index 1 to 2 
      println(sample[4..2]);//Prints a string starting from Index 4 back to 2 
      
   } 
}

当我们运行上面的程序时，我们将得到以下结果-

o 
d 
el 
oll

基本字符串操作

首先，让我们学习groovy中的基本字符串操作。它们在下面给出。

S.No. String Operation & Description
1 Concatenation of two strings

The concatenation of strings can be done by the simple ‘+’ operator.
2 String Repetition

The repetition of strings can be done by the simple ‘*’ operator.
3 String Length

The length of the string determined by the length() method of the string.

字符串方法

这是String类支持的方法的列表。

S.No. Methods & Description
1 center()

Returns a new String of length numberOfChars consisting of the recipient padded on the left and right with space characters.
2 compareToIgnoreCase()

Compares two strings lexicographically, ignoring case differences.
3 concat()

Concatenates the specified String to the end of this String.
4 eachMatch()

Processes each regex group (see next section) matched substring of the given String.
5 endsWith()

Tests whether this string ends with the specified suffix.
6 equalsIgnoreCase()

Compares this String to another String, ignoring case considerations.
7 getAt()

It returns string value at the index position
8 indexOf()

Returns the index within this String of the first occurrence of the specified substring.
9 matches()

It outputs whether a String matches the given regular expression.
10 minus()

Removes the value part of the String.
11 next()

This method is called by the ++ operator for the class String. It increments the last character in the given String.
12 padLeft()

Pad the String with the spaces appended to the left.
13 padRight()

Pad the String with the spaces appended to the right.
14 plus()

Appends a String
15 previous()

This method is called by the — operator for the CharSequence.
16 replaceAll()

Replaces all occurrences of a captured group by the result of a closure on that text.
17 reverse()

Creates a new String which is the reverse of this String.
18 split()

Splits this String around matches of the given regular expression.
19 subString()

Returns a new String that is a substring of this String.
20 toUpperCase()

Converts all of the characters in this String to upper case.
21 toLowerCase()

Converts all of the characters in this String to lower case.