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拡張可能な配列、つまり、配列リストのように容量を増やすことができる配列を作成しようとしています。以下のコードで警告が表示されます。修正する必要がありますか？それを抑制することの結果は何ですか？

import java.util.*;

public class GrowableArray<T>{
  private T[] array;
  //more variables

GrowableArray{
  this.array = (T[]) new Object[10]; // Warning - Type safety: Unchecked cast 
                                     //from Object[] to T[]
  //more code

 }     

//more code

完全なコードについては、以下をご覧ください - 

import java.util.*;  

public class GrowableArray<T>{  

    private T[] array;  
    private int increaseSizeBy;  
    private int currentIndex;//That is first free position available  
    private int lastIndex;  

    public GrowableArray(){       
        this.array = (T[]) new Object[10];  
        this.currentIndex = 0;  
        this.lastIndex = 10-1;  
        this.increaseSizeBy = 10;  
    }  


    public GrowableArray(int initialSize){  
        this.array = (T[]) new Object[initialSize];  
        currentIndex = 0;  
        lastIndex = initialSize - 1;  

    }  

    public void increaseSizeBy(int size){  
        this.increaseSizeBy = size;  

    }  


    public void add(T anObject){  

        if(currentIndex > lastIndex){ ;  
            //create a bigger array  
            int oldLength = array.length;  
            int newLength = oldLength + this.increaseSizeBy;  
            Object [] biggerArray = Arrays.copyOf(array, newLength);  
            array = (T[]) biggerArray;  
            currentIndex = oldLength;  
            lastIndex = array.length-1;  

        }else{  
            array[currentIndex] = anObject;  
            currentIndex++;  

        }  

    }  


    public void display(){  

        System.out.println();  

        for(int i = 0; i < this.currentIndex; i++){  
            System.out.print(array[i] + ", ");  

        }  

        System.out.println();  

    }  


    public static void main(String[]args){  

        GrowableArray<Integer> gArr = new GrowableArray<Integer>();  

        for(int i = 0; i <= 35; i++){  
            gArr.add(i);  

        }  

        gArr.display();  

        gArr.add(300);  
        gArr.add(301);  
        gArr.add(302);  
        gArr.add(303);  
        gArr.add(304);  
        gArr.add(305);  


        gArr.display();  

    }  


}
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1 に答える 1

2

Java 7 では、varargs を使用できます。抑制なし:

public class GrowableArray<T> {
  // Default empty to size 10.
  private static final int DefaultLength = 10;
  // My current array.
  private T[] array;

  // Empty constructor.
  GrowableArray () {
    // Passing no 2nd param at all forces jvm to manufacture an empty one for me - which is an array<T>.
    array = makeNew(DefaultLength);
  }

  // Make a new one of the right size.
  private T[] makeNew(int length, T... sample) {
    return Arrays.copyOf(sample, length);
  }
}
于 2013-04-14T00:22:05.853 に答える