Excercise 9_1_package excercise04; import java.util.arrays; impo-优快云博客

本文链接：https://blog.youkuaiyun.com/caihualin/article/details/391609

博客展示了Java代码，包含一个DoubleGenerator接口、Array2工具类和TestArray2测试类。Array2类有打印数组、填充数组等方法，TestArray2类对其进行测试，通过随机数填充数组并打印不同范围的数组内容。

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//:DoubleGenerator.java

package com.caihualin.util;

public interface DoubleGenerator{
double next();
}///:~

//:Array2.java

package com.caihualin.util;

import java.util.*;

public class Array2{
private static void start(int from,int to,int length){
  if (from!=0||to!=length)
   System.out.print("["+from+":"+to+"]");
  System.out.print("(");
}

private static void end(){
System.out.println(")");
}

public static void print(double[] a){
print(a,0,a.length);
}

public static void print(String msg,double[] a){
System.out.print(msg+" ");
print(a,0,a.length);
}

public static void print(double[] a,int from,int to){
  start(from,to,a.length);
  for (int i=from;i<to;i++){
   System.out.print(a[i]);
   if (i<to-1)
    System.out.print(",");
  }
  end();
}

public static void fill(double[] a,DoubleGenerator gen){
  fill(a,0,a.length,gen);
}

public static void fill(double[] a,int from,int to,DoubleGenerator gen){
  for (int i=from;i<to;i++)
   a[i]=gen.next();
}

private static Random r=new Random();

public static class RandDoubleGenerator implements DoubleGenerator{
  public double next(){
   return r.nextDouble();
  }
}
}

//:TestArray2.java

import com.caihualin.util.*;

public class TestArray2{
public static void main(String[] args){
  int size=6;
  if (args.length!=0)
   size=Integer.parseInt(args[0]);
  double[] a1=new double[size];
  Array2.fill(a1,new Array2.RandDoubleGenerator());
  Array2.print(a1);
  Array2.print("a1=",a1);
  Array2.print(a1,size/3,size/3+size/3);
}
}