String类的常用方法演示

public class Demo2 {
	static String str = new String("I love you!");
	public static void main(String args[]){
		//使用public boolean isEmpty()
		if(!str.isEmpty()){
			System.out.println(str);
		}else{
			System.out.println("There is no text to show");
			}
		//out:I love you!
		//使用public int codePointAt(int index)
		for(int i = 0 ; i < str.length() ; i ++){
			System.out.println("字母\"" + str.charAt(i) + 
					"\"的ASCII码是:" + str.codePointAt(i));
		}
		/*
		  	字母"I"的ASCII码是:73
			字母" "的ASCII码是:32
			字母"l"的ASCII码是:108
			字母"o"的ASCII码是:111
			字母"v"的ASCII码是:118
			字母"e"的ASCII码是:101
			字母" "的ASCII码是:32
			字母"y"的ASCII码是:121
			字母"o"的ASCII码是:111
			字母"u"的ASCII码是:117
			字母"!"的ASCII码是:33
		*/
		System.out.println("字符串" + "\"" + str + "\"" +
				"的第一个字母的ASSCI码是：" + str.codePointBefore(1) + " ");
		//out:字符串"I love you!"的第一个字母的ASSCI码是：73 
		System.out.println("字符串" + "\"" + str + "\"" + "的长度是:" +
				str.codePointCount(0,str.length()));
		//out:字符串"I love you!"的长度是:11
		System.out.println(new String("I love you,").concat("vividle!"));
		//out:I love you,vividle!
		
		//使用public int compareTo(String anotherString)
		if(0 == new String("love").compareTo("Love")){
			System.out.println("the two String is the same.");
		}else{
			System.out.println("the two String isn't the same.");
		}
		//out:the two String isn't the same.
		if(0 == new String("love").compareToIgnoreCase("Love")){
			System.out.println("if we ignore case ,the two String is the same.");
		}else{
			System.out.println("the two String isn't the same.");
		}
		//out:if we ignore case ,the two String is the same.
		//使用public boolean matches(String regex)
		System.out.println(new String("match").matches("match"));//out:true
		System.out.println(new String("matche").regionMatches(0,"match",0,6));//out:false
		System.out.println(new String("match").regionMatches(true,0,"Match",0,5));//out:true
		//使用public int offsetByCodePoints(int index, int codePointOffset)
		String abcdef = new String(new char[]{97,98,99,100,101,102});
		int index = abcdef.offsetByCodePoints(abcdef.length(),-3); 
		System.out.println(index);//out:3
		int cp = abcdef.codePointAt(index); 
		System.out.println(cp);//out:100
		//使用 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
		char[] chget = new char[11];
		str.getChars(0, 11, chget, 0);
		System.out.println(chget);//out:I love you!
		//使用ublic boolean contentEquals(StringBuffer sb)
		System.out.println(str.contentEquals(new StringBuffer("I don't love you!")));//out:false
		//使用public boolean startsWith(String prefix, int toffset)
		System.out.println(str.startsWith("I",0));//out:true
		System.out.println(str.hashCode());//out:-1503998791
		// public int indexOf(String str, int fromIndex)
		System.out.println(str.indexOf("l",0));//out:2
		// public CharSequence subSequence(int beginIndex, int endIndex)
		System.out.println(str.subSequence(0,11).toString());//out:I love you!
		//public String replace(char oldChar, char newChar)
		System.out.println(str.replace(' ','*'));//out:I*love*you!
		//public String replaceFirst(String regex, String replacement)
		System.out.println(str.replaceFirst(" ","*"));//out:I*love you!
		// public String replaceAll(String regex, String replacement)
		System.out.println(str.replaceAll(" ","*"));//out:I*love*you!
		//public String[] split(String regex, int limit)
	
		String[] strArray = new String[]{};
		strArray = str.split(" ",0);
		for(String x :strArray){
			System.out.println(x);
		}
		/*
		 *  I
			love
			you! */

	}
	
}