java中常用的字符串的比较方法（两种）

public class TestString{
  public static void main(String[] args){
   String str1 = "张三";
   String str2 = "张三";
   System.out.println(str1 == str2); //返回true
   System.out.println(str1.equals(str2)); //返回true
   String str3 = new String("李四");
   String str4 = new String("李四");
   System.out.println(str3 == str4); //返回false
   System.out.println(str3.equals(str4)); //返回true
 } 
}