Java-需要帮助解决错误吗
我目前正在学习Java,在我的内部类练习中,我使用了以下代码:Java-需要帮助解决错误吗,java,inner-classes,Java,Inner Classes,我目前正在学习Java,在我的内部类练习中,我使用了以下代码: public class DataStructure { // Create an array private final static int SIZE = 15; private int[] arrayOfInts = new int[SIZE]; public DataStructure() { // fill the array with ascending integer
public class DataStructure {
// Create an array
private final static int SIZE = 15;
private int[] arrayOfInts = new int[SIZE];
public DataStructure() {
// fill the array with ascending integer values
for (int i = 0; i < SIZE; i++) {
arrayOfInts[i] = i;
}
}
public void printEven() {
// Print out values of even indices of the array
DataStructureIterator iterator = this.new EvenIterator();
while (iterator.hasNext()) {
System.out.print(iterator.next() + " ");
}
System.out.println();
}
interface DataStructureIterator extends java.util.Iterator<Integer> { }
// Inner class implements the DataStructureIterator interface,
// which extends the Iterator<Integer> interface
private class EvenIterator implements DataStructureIterator {
// Start stepping through the array from the beginning
private int nextIndex = 0;
public boolean hasNext() {
// Check if the current element is the last in the array
return (nextIndex <= SIZE - 1);
}
public Integer next() {
// Record a value of an even index of the array
Integer retValue = Integer.valueOf(arrayOfInts[nextIndex]);
// Get the next even element
nextIndex += 2;
return retValue;
}
public void setNextIndex(int i){
nextIndex=i;
}
}
public void print(DataStructureIterator iterator) {
// Print out values of odd indices of the array
//iterator = this.new EvenIterator();
iterator.setNextIndex(1);//**This line giving me compiler error that setNextIndex is undefined for type DataStructure.DataStructureIterator **
while (iterator.hasNext()) {
System.out.print(iterator.next() + " ");
}
System.out.println();
}
public EvenIterator createNewObject(){
return this.new EvenIterator();
}
public static void main(String s[]) {
// Fill the array with integer values and print out only
// values of even indices
DataStructure ds = new DataStructure();
System.out.println("Even Index");
ds.printEven();
System.out.println("Odd Index");
ds.print(ds.createNewObject());
}
}
公共类数据结构{
//创建一个数组
私有最终静态整数大小=15;
private int[]arrayOfInts=新的int[SIZE];
公共数据结构(){
//用升序整数值填充数组
对于(int i=0;i return(nextIndexprint
方法知道它的参数是一个DataStructureIterator
。setNextIndex
方法是在该接口中声明的吗?如果不是,你必须添加它。即使你将EvenIterator
传递给方法print(DataStructureIterator)
,它将以静默方式转换到数据结构迭代器中
方法未在DataStructureIterator
中声明,您将无法访问它。您可以共享DataStructureIterator接口吗?由于DataStructureIterator持有object EvenIterator,它应该能够访问setNextIndex,但编译器不知道。它只看到该方法(可以使用另一个不提供该方法的DataStructureIterator调用该方法)。要么在接口中声明该方法(preferrable),要么在print中执行显式转换。