掃描儀類的next()方法 (Scanner Class next() method)

Syntax:

句法：

    public String next();
public String next(Pattern patt);
public String next(String patt);

• next() method is available in java.util package.

  next()方法在java.util包中可用。

• next() method is used to search & get the next complete token from this Scanner and a token is preceded & followed by the input that meets the pattern.

  next()方法用于搜索并從此掃描器中獲取下一個完整令牌，令牌之前和之后是符合模式的輸入。

• next(Pattern patt) method is used to retrieve the next token when it meets the given Pattern (patt).

  next(Pattern patt)方法用于在遇到給定Pattern(patt)時檢索下一個標記。

• next(String patt) method is used to retrieve the next token when it meets the pattern formed from the given String (patt).

  next(String patt)方法用于在下一個令牌遇到由給定String(patt)形成的模式時檢索下一個令牌。

• These methods may throw an exception at the time of representing a token as a pattern.

  這些方法在將令牌表示為模式時可能會引發異常。

  • NoSuchElementException: This exception may throw when no more token exists.NoSuchElementException ：如果不再存在令牌，則可能引發此異常。
  • IllegalStateException: This exception may throw when this Scanner is not opened.IllegalStateException ：如果未打開此掃描器，則可能引發此異常。

• These are non-static methods, it is accessible with class object & if we try to access these methods with the class name then we will get an error.

  這些是非靜態方法，可通過類對象訪問；如果嘗試使用類名稱訪問這些方法，則會收到錯誤消息。

Parameter(s):

參數：

• In the first case, next(),

  在第一種情況下， next() ，

  • It does not accept any parameter.

• In the first case, next(Pattern patt),

  在第一種情況下， next(Pattern patt) ，

  • Pattern patt – represents the pattern (patt) to read.
  • 模式patt –表示要讀取的模式(patt)。

• In the second case, next(String patt),

  在第二種情況下， next(String patt) ，

  • String patt – represents the string to define the pattern (patt) to read.
  • 字符串patt –表示用于定義要讀取的圖案(圖案)的字符串。

Return value:

返回值：

In all the cases, the return type of the method is String, it retrieves the next token

在所有情況下，方法的返回類型為String ，它檢索下一個標記

Example 1:

范例1：

// Java program is to demonstrate the example 
// of next() method of Scanner
import java.util.*;
import java.util.regex.*;
public class Next {
public static void main(String[] args) {
String str = "Java Programming! 3 * 8= 24";
// Instantiates Scanner
Scanner sc = new Scanner(str);
// By using next() method is to
// display the next complete 
// token
String next = sc.next();
System.out.println("sc.next(): " + next);
// Scanner closed
sc.close();
}
}

Output

輸出量

sc.next(): Java

Example 2:

范例2：

import java.util.*;
import java.util.regex.*;
public class Next {
public static void main(String[] args) {
String str = "Java Programming! 3 * 8= 24";
// Instantiates Scanner
Scanner sc = new Scanner(str);
// By using net(Pattern) method is
// to return the next token when it meets
// the given pattern
String next_p = sc.next(Pattern.compile("J..a"));
System.out.println("sc.next(Pattern.compile(J..a)): " + next_p);
// Scanner closed
sc.close();
}
}

Output

輸出量

sc.next(Pattern.compile(J..a)): Java

Example 3:

范例3：

import java.util.*;
import java.util.regex.*;
public class Next {
public static void main(String[] args) {
String str = "Java Programming! 3 * 8= 24";
// Instantiates Scanner
Scanner sc = new Scanner(str);
// By using net(String) method is
// to return the next token when it meets
// the given pattern formed from the given
// string
String next_s = sc.next("Java");
System.out.println("sc.next(Java)): " + next_s);
// Scanner closed
sc.close();
}
}

Output

輸出量

sc.next(Java)): Java

翻譯自: https://www.includehelp.com/java/scanner-next-method-with-example.aspx