Java MessageFormat setFormatsByArgumentIndex()用法及代码示例

java.text.MessageFormat类的setFormatsByArgumentIndex方法用于通过覆盖旧模式来设置消息格式对象模式中新格式元素的数组。

用法:

public void setFormatsByArgumentIndex(Format[] newFormats)

参数：此方法采用格式元素数组作为参数，以覆盖邮件格式对象的旧模式。

返回值：此方法无返回值。

异常：如果新格式元素的数组为null，则此方法引发NullPointerException。

下面是说明setFormatsByArgumentIndex()方法的示例：

范例1：

// Java program to demonstrate 
// setFormatsByArgumentIndex() 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, date, #}, {2, number, #.##}, {4, time}"); 
  
            // display the current message format object 
            displayFormat(mf); 
  
            // creating and initializing new Format object array 
            Format[] format = { new SimpleDateFormat("YYYY-'W'ww-u"), 
                                new DecimalFormat("10.5678") }; 
  
            // settting the new array of formats 
            // in the pattern of MessageFormat object 
            // using setFormatsByArgumentIndex() method 
            mf.setFormatsByArgumentIndex(format); 
  
            // display the Override MessageFormat object 
            System.out.println(); 
            displayFormat(mf); 
        } 
        catch (NullPointerException e) { 
            System.out.println("format array is null"); 
            System.out.println("Exception thrown:" + e); 
        } 
    } 
  
    // Defining displayFormat method 
    public static void displayFormat(MessageFormat mf) 
    { 
  
        // display the result 
        System.out.println("pattern:"
                           + mf.toPattern()); 
  
        // getting all format 
        // used in MessageFormat Object 
        // using getFormats() method 
        Format[] formats = mf.getFormats(); 
  
        // display the result 
        System.out.println("Required Formats are:"); 
        for (int i = 0; i < formats.length; i++) 
            System.out.println(formats[i]); 
    } 
}

输出：

pattern:{0, date, #}, {2, number, #0.##}, {4, time}
Required Formats are:
java.text.SimpleDateFormat@403
java.text.DecimalFormat@674fc
java.text.SimpleDateFormat@8400729

pattern:{0, date, YYYY-'W'ww-u}, {2, number, #0.##}, {4, time}
Required Formats are:
java.text.SimpleDateFormat@d21287d2
java.text.DecimalFormat@674fc
java.text.SimpleDateFormat@8400729

范例2：

// Java program to demonstrate 
// setFormatsByArgumentIndex() 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, date, #}, {2, number, #.##}, {4, time}"); 
  
            // display the current message format object 
            displayFormat(mf); 
  
            // creating and initializing new Format object array 
            Format[] format = { new SimpleDateFormat("YYYY-'W'ww-u"), 
                                new DecimalFormat("10.5678") }; 
  
            // settting the new array of formats 
            // in the pattern of MessageFormat object 
            // using setFormatsByArgumentIndex() method 
            mf.setFormatsByArgumentIndex(null); 
  
            // display the Override MessageFormat object 
            System.out.println(); 
            displayFormat(mf); 
        } 
        catch (NullPointerException e) { 
            System.out.println("\nformat array is null"); 
            System.out.println("Exception thrown:" + e); 
        } 
    } 
  
    // Defining displayFormat method 
    public static void displayFormat(MessageFormat mf) 
    { 
  
        // display the result 
        System.out.println("pattern:"
                           + mf.toPattern()); 
  
        // getting all format 
        // used in MessageFormat Object 
        // using getFormats() method 
        Format[] formats = mf.getFormats(); 
  
        // display the result 
        System.out.println("Required Formats are:"); 
        for (int i = 0; i < formats.length; i++) 
            System.out.println(formats[i]); 
    } 
}

输出：

pattern:{0, date, #}, {2, number, #0.##}, {4, time}
Required Formats are:
java.text.SimpleDateFormat@403
java.text.DecimalFormat@674fc
java.text.SimpleDateFormat@8400729

format array is null
Exception thrown:java.lang.NullPointerException

参考： https://docs.oracle.com/javase/9/docs/api/java/text/MessageFormat.html#setFormatsByArgumentIndex-java.text.Format:A-

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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 setFormatsByArgumentIndex() method in Java with Example。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。