package seday01;
/**
* 字符串是不變對象,內容一旦創建不可改變,若改變一定會創建新對象
* @author xingsir
*/
public class StringDemo {
public static void main(String[] args) {
String s1="Hello Java";
String s2="Hello Java";
System.out.println(s1==s2);//true
String s3="Hello Java";//true
System.out.println(s1==s3);//true
s1=s1+"!!!";//當s1修改內容時會創建新對象
System.out.println("s1:"+s1);//此時輸出為s1:Hello Java!!!
System.out.println("s2:"+s2);//輸出：s2:Hello Java
System.out.println(s2==s3);//true
System.out.println(s1==s2);//false
/*
* new創建的字符串對象並不會重用
*/
String s4= new String("Hello Java");
System.out.println(s4);//Hello Java
System.out.println(s2==s4);//false
System.out.println(s2.equals(s4));//true
}
}