stringdemo.java

java课程的资料以及实验的代码

public class StringDemo {

	/**
	 * @param args
	 */
	String str;
	public StringDemo()
	{
		str="";
	}
	public StringDemo(String str)
	{
		this.str=str;
	}
	public void methodDemo()
	{
		System.out.println("CharAt():"+str.charAt(1));
		System.out.println("indexOf():"+str.indexOf("good"));
		System.out.println("LastIndexOf():"+str.lastIndexOf("hi"));
		System.out.println("SubString():"+str.substring(2,19));
		String str1="Good";
		String str2="good";
		String str3=new String("Good");
		String str4="Good";
		System.out.println("str1==str2:"+(str1==str2));
		System.out.println("str1==str3:"+(str1==str3));
		System.out.println("str1==str4:"+(str1==str4));
		System.out.println("str1.equals str3:"+str1.equals(str3));
		System.out.println("toLowerCase():"+str1.toLowerCase());
		System.out.println("toUpperCase():"+str3.toUpperCase());
	}
	public void  diffrentStringandStringBuffer()
	{
		String ss=new String("a");
		long start=System.currentTimeMillis();
		for(int i=0;i<50000;i++)
			ss+='a';
		System.out.println("String time:"+(System.currentTimeMillis()-start));
		StringBuffer sbf=new StringBuffer("a");
		 start=System.currentTimeMillis();
		for(int i=0;i<50000;i++)
			sbf.append('a');
		System.out.println("StringBuffer time:"+(System.currentTimeMillis()-start));
	}
	public void splitTest(String str)
	{
		String []dem=str.split(",");
		for(int i=0;i<dem.length;i++)
		{
			System.out.println(dem[i]);
		}
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		StringDemo sd=new StringDemo(" hi good good MOring hi");
		sd.methodDemo();
		sd.diffrentStringandStringBuffer();
		sd.splitTest(args[0]);

	}

}