String创建对象的个数--西北狼

public class StringDemo {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
/*第一题：String str = new String("abc");创建了几个对象
第二题： String s="a"+"b"+"c"+"d"创建了几个对象（假设之前串池是空的）
第三题：StringBuilder sb = new StringBuilder();
String a = "a";
String b = "b";
String c = "c";
String d = "d";
String s = a+b+c+d;  这句话创建了几个对象
第四题：StringBuilder sb = new StringBuilder();
sb.append("a").append("b").append("c").append("d");这句话创建了几个对象*/

String str = new String("abc");
String s = "a" + "b" + "c" + "d"; //创建了几个对象（假设之前串池是空的）
StringBuilder sb = new StringBuilder();
String a = "a";
String b = "b";
String c = "c";
String d = "d";
String s2 = a + b + c + d;
StringBuilder sb2 = new StringBuilder();
sb2.append("a").append("b").append("c").append("d");

if(str instanceof Object){
System.out.println("str是对象");
}else{
System.out.println("str不是对象");
}
System.out.println("-------------------------");
if(s instanceof Object){
System.out.println("s是对象");
}else{
System.out.println("s不是对象");
}
System.out.println("-------------------------");
if(a instanceof Object){
System.out.println("a是对象");
}else{
System.out.println("a不是对象");
}

if(sb instanceof Object){
System.out.println("sb是对象");
}else{
System.out.println("sb不是对象");
}

}

}

转载于:https://www.cnblogs.com/childhooding/p/4693597.html