Java代码案例29——字符串相等比较时需要使用equals函数

package xiangmu;
public class Ceshi {
    public static void main(String args[]) {
        String zfc1 = "ab";
        String zfc2 = "ab";
        dayin("zfc1: " + zfc1);
        dayin("zfc2: " + zfc2);
        dayin("1. zfc1 == zfc2       " + (zfc1 == zfc2));
        dayin("2. zfc1.equals(zfc2)  " + (zfc1.equals(zfc2)));
        zfc1 = zfc1 + "c";
        zfc2 = zfc2 + "c";
        dayin("zfc1: " + zfc1);
        dayin("zfc2: " + zfc2);
        dayin("3. zfc1 == zfc2       " + (zfc1 == zfc2));   // 引用类型不能用 == 比较是否相等
        dayin("4. zfc1.equals(zfc2)  " + (zfc1.equals(zfc2)));  // 引用类型使用 equals 函数比较是否相等
    }
    public static void dayin(Object obj) {
        System.out.println(obj);
    }
}
zfc1: ab
zfc2: ab
1. zfc1 == zfc2       true
2. zfc1.equals(zfc2)  true
zfc1: abc
zfc2: abc
3. zfc1 == zfc2       false
4. zfc1.equals(zfc2)  true