Java MessageFormat parse()函数用法及代码示例

java.text.MessageFormat类的parse()方法用于从parse()方法中传递的解析位置开始解析字符串对象。

用法:

public Object[] parse(String source,
                      ParsePosition pos)

参数：此方法采用以下参数作为参数。

source:-将要执行解析的字符串。
pos:-它是解析的起始索引。

返回值：此方法返回对象数组作为输出。

异常：如果解析位置为null，则此方法引发NullPointerException。

下面是说明parse()方法的示例：

范例1：

// Java program to demonstrate 
// parse() method 
  
import java.text.*; 
import java.util.*; 
import java.io.*; 
  
public class GFG { 
    public static void main(String[] argv) 
    { 
        try { 
            // creating and initializing  MessageFormat 
            MessageFormat mf 
                = new MessageFormat("{0, number, #}, {2, number, #.#}, {1, number, #.##}"); 
            ; 
  
            // creating and initializing String source 
            String str = "10.456, 20.325, 30.444"; 
  
            // creating and initializing ParsePosition 
            ParsePosition pos = new ParsePosition(3); 
  
            // parsing the string starting from pos 
            // accoridng to MessageFormat 
            // using parse() method 
            Object[] hash = mf.parse(str, pos); 
  
            // display the result 
            System.out.println("Parsed value are:"); 
            for (int i = 0; i < hash.length; i++) 
                System.out.println(hash[i]); 
        } 
        catch (NullPointerException e) { 
            System.out.println("\nParse position is Null"); 
            System.out.println("Exception thrown:" + e); 
        } 
    } 
}

输出：

Parsed value are:
456
30.444
20.325

范例2：

// Java program to demonstrate 
// parse() method 
  
import java.text.*; 
import java.util.*; 
import java.io.*; 
  
public class GFG { 
    public static void main(String[] argv) 
    { 
        try { 
            // creating and initializing  MessageFormat 
            MessageFormat mf 
                = new MessageFormat("{0, number, #}, {2, number, #.#}, {1, number, #.##}"); 
  
            // creating and initializing String source 
            String str = "10.456, 20.325, 30.444"; 
  
            // creating and initializing ParsePosition 
            // ParsePosition pos = new ParsePosition(3); 
  
            // parsing the string starting from pos 
            // accoridng to MessageFormat 
            // using parse() method 
            Object[] hash = mf.parse(str, null); 
  
            // display the result 
            System.out.println("Parsed value are:"); 
            for (int i = 0; i < hash.length; i++) 
                System.out.println(hash[i]); 
        } 
        catch (NullPointerException e) { 
            System.out.println("Parse position is Null"); 
            System.out.println("Exception thrown:" + e); 
        } 
    } 
}

输出：

Parse position is Null
Exception thrown:java.lang.NullPointerException

参考：https://docs.oracle.com/javase/9/docs/api/java/text/MessageFormat.html#parse-java.lang.String-java.text.ParsePosition-

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注：本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 MessageFormat parse() method in Java with Example : Set – 2。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。