字串類的基本用法
阿新 • • 發佈:2021-08-14
/**
測試字串類的基本用法
*/
public class TestString { public static void main(String[] args) { String str1 = "abc"; String str2 = new String("def"); String str3 = "abc" + "defgh"; String str4 = "18" + 19; //這不是加法,是連線符 System.out.println(str4); //1819 String str10 = "abcc"; String str11 = "abcc"; String str12 = new String("abcc"); System.out.println(str10 == str11);//true System.out.println(str12 == str11); //false,str11和str12不同物件 //字串對比需要使用equals System.out.println(str12.equals(str11));//true String s1 = "core Java"; String s2 = "Core Java"; System.out.println(s1.charAt(3)); //e,提取下標為3的字元 System.out.println(s2.length()); //9,字串的長度 System.out.println(s1.equals(s2)); //false,比較兩個字串是否相等 System.out.println(s1.indexOf("Java")); //5,字串s1中是否包含Java System.out.println(s1.indexOf("apple")); //-1,字串s1中是否包含apple String s = s1.replace(' ','&'); //將s1的空格替換成& System.out.println("result is :"+s); System.out.println(s1); //不改變s1本身 String ss1 = ""; String ss2 = "How are you"; System.out.println(ss1.startsWith("How")); //是否以How開頭 System.out.println(ss1.endsWith("you")); //是否以you結尾 ss1=ss2.substring(4);//提取字串:從下標為4的開始到字串結尾為止 System.out.println(ss1);//are you //String sss3 = "How old are you?"; //ss1 = s2.trim(); //去除字串首尾的空格 //ss1 = ss3.toLowerCase();//轉小寫 //ss1 = ss3.toUpperCase();//轉大寫 } }