Java Vector setSize()方法及实例

Java.util.Vector. setSize() 是Vector类的一个方法，用来设置向量的新大小。如果向量的新大小大于当前大小，那么空元素将被添加到向量中，如果新大小小于当前大小，那么所有高阶元素将被删除。

该方法将向量的大小修改为newSize，并且不返回任何东西。

语法

public void setSize(int newSize)

参数： 该方法接受一个矢量的强制性参数 newSize。

返回类型： NA

异常: ArrayIndexOutOfBoundsException

注意： 如果新的大小是负数，那么它将抛出 运行时错误。

例子1 :

// Java Program to Illustrate setSize() method
// of Vector class
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
 
        // Creating object of Vector class
        // Declaring object of string type
        Vector<String> v = new Vector<String>();
 
        // Inserting elements into the vector
        // using add() method
        // Custom input elements
        v.add("Geeks");
        v.add("for");
        v.add("Geeks");
        v.add("Computer");
        v.add("Science");
        v.add("Portal");
 
        // Printing vector before calling setSize() method
        System.out.println("Initially");
        System.out.println("Vector: " + v);
        System.out.println("Size: " + v.size());
 
        // Setting new custom size
        v.setSize(8);
 
        // Printing vector after calling setSize()
        System.out.println("\nAfter using setSize()");
        System.out.println("Vector: " + v);
        System.out.println("Size: " + v.size());
    }
}

输出

Initially
Vector: [Geeks, for, Geeks, Computer, Science, Portal]
Size: 6

After using setSize()
Vector: [Geeks, for, Geeks, Computer, Science, Portal, null, null]
Size: 8

例2： 当新尺寸为正时

// Java program to Illustrate setSize() method
// of Vector class
// Where size is positive
 
// Importing utility classes
import java.util.*;
 
// Main class
public class GFG {
 
    // amin driver method
    public static void main(String[] args)
    {
        // Creating vector object of string type
        Vector<String> v = new Vector<String>();
 
        // Inserting elements into the vector
        //. using add() method
        // Custom input elements
        v.add("Geeks");
        v.add("for");
        v.add("Geeks");
        v.add("Computer");
        v.add("Science");
        v.add("Portal");
 
        // Printing vector before calling setSize()
        System.out.println("Initially");
        System.out.println("Vector: " + v);
        System.out.println("Size: " + v.size());
 
        // Setting new size
        v.setSize(4);
 
        // Printing vector after calling setSize()
        System.out.println("\nAfter using setSize()");
        System.out.println("Vector: " + v);
        System.out.println("Size: " + v.size());
    }
}

输出

Initially
Vector: [Geeks, for, Geeks, Computer, Science, Portal]
Size: 6

After using setSize()
Vector: [Geeks, for, Geeks, Computer]
Size: 4

例3： 当新尺寸为负数时

// Java program to Illustrate setSize() method
// of vector class
// Where size is negative
 
// Importing utility classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating Vector class object of string type
        Vector<String> v = new Vector<String>();
 
        // Inserting elements into the vector
        // using add() method
        v.add("Geeks");
        v.add("for");
        v.add("Geeks");
        v.add("Computer");
        v.add("Science");
        v.add("Portal");
 
        // Printing vector before calling setSize()
        System.out.println("Initially");
        System.out.println("Vector: " + v);
        System.out.println("Size: " + v.size());
 
        // Try block to check for exceptions
        try {
 
            // Setting new size
            v.setSize(-8);
        }
 
        // Catch block to handle exceptions
        catch (Exception e) {
 
            // Display message when exceptions occurred
            System.out.println("Trying to change "
                               + "size to '-8'\n" + e);
        }
    }
}

输出