本文共 2137 字，大约阅读时间需要 7 分钟。
1. 通过类对象调用newInstance()方法，适用于无参构造方法：
例如：String.class.newInstance()
1 public class Solution { 2 3 public static void main(String[] args) throws Exception { 4 5 Solution solution = Solution.class.newInstance(); 6 7 Solution solution2 = solution.getClass().newInstance(); 8 9 Class solutionClass = Class.forName("Solution");10 Solution solution3 = (Solution) solutionClass.newInstance();11 12 System.out.println(solution instanceof Solution); //true13 System.out.println(solution2 instanceof Solution); //true14 System.out.println(solution3 instanceof Solution); //true15 }16 18 }
2. 通过类对象的getConstructor()或getDeclaredConstructor()方法获得构造器（Constructor）对象并调用其newInstance()方法创建对象，适用于无参和有参构造方法。
例如：String.class.getConstructor(String.class).newInstance("Hello");
1 public class Solution { 2 3 private String str; 4 private int num; 5 6 public Solution() { 7 8 } 9 10 public Solution(String str, int num) {11 this.str = str;12 this.num = num;13 }14 15 public Solution(String str) {16 this.str = str;17 }18 19 public static void main(String[] args) throws Exception {20 21 Class[] classes = new Class[] { String.class, int.class };22 Solution solution = Solution.class.getConstructor(classes).newInstance("hello1", 10);23 System.out.println(solution.str); // hello124 25 Solution solution2 = solution.getClass().getDeclaredConstructor(String.class).newInstance("hello2");26 System.out.println(solution2.str); // hello227 28 Solution solution3 = (Solution) Class.forName("Solution").getConstructor().newInstance(); // 无参也可用getConstructor()29 System.out.println(solution3 instanceof Solution); // true30 }31 32 }
********* getConstructor()和getDeclaredConstructor()区别：*********
转载地址：http://mntni.baihongyu.com/