不同类型的对象比较不相等(字符串与包装类比较)

public class LongCompareStringTest {
	public static void main(String[] args) {
		Long data = 0l;
		
		System.out.println(data.toString());
		
		if ("0".equals(data)) { // 得到false1
			System.out.println("true1");
		} else {
			System.out.println("false1");
		}
		
		if (0l == data) { // 得到true2
			System.out.println("true2");
		} else {
			System.out.println("false2");
		}
	}
}

调用equals方法时,首先判断实例类型，不同实例，直接返回false
String#equals

public boolean equals(Object anObject) {
        if (this == anObject) {
            return true;
        }
        if (anObject instanceof String) {
            String anotherString = (String) anObject;
            int n = value.length;
            if (n == anotherString.value.length) {
                char v1[] = value;
                char v2[] = anotherString.value;
                int i = 0;
                while (n-- != 0) {
                    if (v1[i] != v2[i])
                            return false;
                    i++;
                }
                return true;
            }
        }
        return false;
    }