在成员方法的反射这节遇到的问题 - 黑马程序员技术交流社区

public class ReflectTest {
public static void main(String[] args) throws Exception {
Constructor<String> constructor = String.class.getConstructor(StringBuffer.class);
String str = (String)constructor.newInstance(new StringBuffer("abc"));
System.out.println(str.charAt(2));
ReflectPoint pt = new ReflectPoint(2,5);
Field fieldY = pt.getClass().getField("y");
System.out.println(fieldY.get(pt));
Field fieldX = pt.getClass().getDeclaredField("x");
fieldX.setAccessible(true);//暴力访问
System.out.println(fieldX.get(pt));
changeStringValue(pt);
System.out.println(pt);
Method methodCharAt = String.class.getMethod("chatAt", int.class);//为嘛我运行的时候就说这句有问题呢？还有对这条语句的作用还是不大明白，哪位给解释一下
System.out.println(methodCharAt.invoke(str, 1));
}
private static void changeStringValue(Object obj) throws Exception {
Field [] fields = obj.getClass().getFields();
for(Field field: fields){
if(field.getType()==String.class){
String oldValue = (String)field.get(obj);
String newValue = oldValue.replace('b','a');
field.set(obj, newValue);
}
}
}
}

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