How to use strings in Java language

Java is a high-level programming language that is widely used in the development of various applications. Among them, string is a very important data type in Java. This article will introduce how to use Java language strings, including creating strings, string comparisons, string concatenation, string interception, etc.

1. Create a string

In Java, you can create a string in two ways. The first way is to use string literals. For example, the following line of code creates a string object with the value "Hello World!":

String str = "Hello World!";

The second method is to use the constructor of the String class. For example, the following line of code uses the constructor to create a string object with the value "Hello World!":

String str = new String("Hello World!");

2. String comparison

In Java , you can use the equals() method to compare whether two strings are equal. For example, the following line of code compares two strings for equality:

String str1 = "Hello";
String str2 = "hello";
if(str1.equals(str2)){
    System.out.println("两个字符串相等");
}else{
    System.out.println("两个字符串不相等");
}

You can also use the equalsIgnoreCase() method to ignore case when comparing strings. For example, the following line of code compares two strings for equality (ignoring case):

String str1 = "Hello";
String str2 = "hello";
if(str1.equalsIgnoreCase(str2)){
    System.out.println("两个字符串相等");
}else{
    System.out.println("两个字符串不相等");
}

3. String concatenation

In Java, there are three ways to do this connection string. The first method is to use the " " operator. For example, the following line of code will concatenate two strings:

String str1 = "Hello";
String str2 = "World";
String str3 = str1 + str2;
System.out.println(str3); //输出HelloWorld

The second method is to use the concat() method. For example, the following line of code will join two strings:

String str1 = "Hello";
String str2 = "World";
String str3 = str1.concat(str2);
System.out.println(str3); //输出HelloWorld

The third method is to use the StringJoiner class. For example, the following line of code will concatenate two strings:

String str1 = "Hello";
String str2 = "World";
StringJoiner sj = new StringJoiner("");
sj.add(str1).add(str2); 
String str3 = sj.toString();
System.out.println(str3); //输出HelloWorld

4. String interception

In Java, you can use the substring() method to intercept strings. For example, the following line of code will intercept part of a string:

String str1 ="Hello World";
String str2 = str1.substring(1, 5);
System.out.println(str2); //输出ello

In addition, you can also use the split() method to split a string into multiple parts. For example, the following line of code will split a string into multiple parts based on spaces:

String str1 ="Hello World";
String[] str2 = str1.split(" ");
for(int i = 0; i < str2.length; i++){
    System.out.println(str2[i]); //输出Hello和World
}

In summary, this article introduces the methods of creating, comparing, concatenating, and intercepting Java language strings. These methods are very important basic knowledge in Java programming. I hope readers can understand and apply them in depth.

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