java速度入门三

数组操作：

compareNew.java

//use the function:sort();binarySearch();fill();equals();
import java.util.Arrays;
import java.util.Comparator;
//define a class that we could ignore the letter's case when sort array
class compareNew implements Comparator
{
    public int compare(Object o1,Object o2)
    {
        String s1=(String)o1;
        String s2=(String)o2;
        return s1.toLowerCase().compareTo(s2.toLowerCase());
    }
   
}

array.java
public class array {
   
    public static void main(String args[])
    {
        int[] aa=new int[10];
        String[] ss=new String[]{"w1","dwT","Aqs","Cda","Bsw","bss"};
        //filling the array
        Arrays.fill(aa,10);
        System.out.println("array a: ");
        for(int i=0;i<aa.length;i++)
        {
            System.out.print(aa[i]);
           
        }
        System.out.println();
        System.out.println("array ss: "+Arrays.asList(ss));
        //sort array by the default setting
        Arrays.sort(ss);
        System.out.println("After sorting ss: "+Arrays.asList(ss));
        System.out.println("Hello,java!");
        //sort array by the our own function
        Arrays.sort(ss,new compareNew());
        System.out.println("Another sorting ss: "+Arrays.asList(ss));
        int location=Arrays.binarySearch(ss, "w1");
        System.out.println("The location of w1 is "+(location+1)+"!");
    }
}
简单实现了数组的搜索，查找，排序。

字符串操作：

Apple.java

//test the connect of String and object
public class Apple {
 private String name;
 public String getName()
 {
     return name;
 }
 public void setName(String s)
 {
     this.name=s;
 }
 public String toString()
 {
     String str="I'm an apple,my name is "+name;
     return str;
 }
 public static void main(String[] args)
 {
     Apple object=new Apple();
     object.setName("App");
     System.out.println("Hello,"+object);
     }
}

TestStringBuilder.java

//The useage of StringBuilder
import java.lang.*;
public class TestStringBuilder {
    public static void main(String[] args)
    {
        String s="";
        StringBuilder builder=new StringBuilder();
        long startTime,endTime;
        System.out.println("Please wait。。。");
        //use the default function
        startTime=System.currentTimeMillis();
        for(int i=0;i<10000;i++) s+=i;
        endTime=System.currentTimeMillis();
        System.out.println("The cost of time: "+(endTime-startTime));
        //use StringBuilder
        startTime=System.currentTimeMillis();
        for(int i=0;i<10000;i++) builder.append(i+"");
        endTime=System.currentTimeMillis();
        System.out.println("The cost of time by StringBuilder: "+(endTime-startTime));
       
    }
}
运行结果：
Please wait。。。
The cost of time: 1371
The cost of time by StringBuilder: 9

主要要说一下字符串和对象的连接，默认是执行对象的toString方法，即将对象的全路径名称和地址，上面重载了toString方法。

第二个class是StringBuilder的用法，似乎会很快！