Java 字符串子序列()方法，示例

原文:https://www . geesforgeks . org/Java-string-subserial-method-examples/

Java . lang . string . subsequence()是 Java 中的一个内置函数，返回一个 CharSequence。这个序列的子序列。子序列以指定索引处的字符值开始，以(end-1)处的字符值结束。返回序列的长度(以字符为单位)是(end-start，所以如果 start == end，则返回一个空序列。

语法:

public CharSequence subSequence(int start, int end) 
Parameters: 
start - This is the index from where the subsequence starts, it is inclusive.
end - This is the index where the subsequence ends, it is exclusive.

返回: 返回范围【开始，结束】内的指定子序列。

错误和异常: indexout of boundsexception–如果开始或结束为负，如果结束大于长度()，或者如果开始大于结束，它会抛出此错误。

程序 1: 展示 Java . lang . string . subsequel()函数的工作原理。

// Java program to demonstrate working
// of Java.lang.String.subSequence() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {

        String Str = "Welcome to geeksforgeeks";

        // prints the subsequence from 0-7, exclusive 7th index
        System.out.print("Returns: ");
        System.out.println(Str.subSequence(0, 7));

        System.out.print("Returns: ");
        System.out.println(Str.subSequence(10, 24));
    }
}

输出:

Returns: Welcome
Returns:  geeksforgeeks

程序 2: 显示当索引为负时 Java.lang.String.subSequence()函数的错误

// Java program to demonstrate error
// of Java.lang.String.subSequence() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {

        String Str = "Welcome to geeksforgeeks";

        // throws an error as index is negative
        System.out.print("Returns: ");
        System.out.println(Str.subSequence(-1, 7));
    }
}

输出:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: 
String index out of range: -1
    at java.lang.String.substring(String.java:1960)
    at java.lang.String.subSequence(String.java:2003)
    at Gfg.main(File.java:15)

程序 3: 显示当索引超出范围时 Java.lang.String.subSequence()函数的错误。

// Java program to demonstrate error
// of Java.lang.String.subSequence() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {

        String Str = "Welcome to geeksforgeeks";

        // throws an error as end is out of range
        System.out.print("Returns: ");
        System.out.println(Str.subSequence(10, 50));
    }
}

输出:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: 
String index out of range: 50
    at java.lang.String.substring(String.java:1963)
    at java.lang.String.subSequence(String.java:2003)
    at Gfg.main(File.java:16)

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