Java中的 FieldPosition setBeginIndex() 方法与示例

Java.text.FieldPosition类的setBeginIndex()方法用于设置FieldPosition 对象的起始字符的索引。
句法：

public void setBeginIndex(int index)

参数：此方法采用整数值索引作为 FieldPosition 对象的起始字符的新索引。
返回值：此方法没有任何返回值。
下面是说明setBeginIndex()方法的示例：
示例 1：

Java

// Java program to demonstrate
// setBeginIndex() method
 
import java.text.*;
import java.util.*;
import java.io.*;
 
public class GFG {
    public static void main(String[] argv)
    {
        try {
 
            // Creating and initializing
            // new FieldPosition Object
            FieldPosition pos
                = new FieldPosition(DateFormat.Field.AM_PM);
 
            // setting begin index of FieldPosition Object
            // using setBeginIndex() method
            pos.setBeginIndex(5);
 
            // getting begin index of FieldPosition Object
            int i = pos.getBeginIndex();
 
            // display result
            System.out.println("begin index :- " + i);
        }
 
        catch (ClassCastException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

begin index :- 5

示例 2：

Java

// Java program to demonstrate
// setBeginIndex() method
 
import java.text.*;
import java.util.*;
import java.io.*;
 
public class GFG {
    public static void main(String[] argv)
    {
        try {
 
            // Creating and initializing
            // new FieldPosition Object
            FieldPosition pos
                = new FieldPosition(
                    MessageFormat.Field.ARGUMENT);
 
            // setting begin index of FieldPosition Object
            // using setBeginIndex() method
            pos.setBeginIndex(10);
 
            // getting begin index of FieldPosition Object
            int i = pos.getBeginIndex();
 
            // display result
            System.out.println("begin index :- " + i);
        }
 
        catch (ClassCastException e) {
 
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出：

begin index :- 10

参考： https://docs.oracle.com/javase/9/docs/api/ Java/text/FieldPosition.html#setBeginIndex-int-