使用JAVA反射時出現NoSuchMethodException

Question

嗨，我正在嘗試使用反射來調用方法並更新該方法的setter值。 但是我在獲取該方法時遇到了NoSuchMethodException。 我已經更新了代碼。 對於先前代碼中的錯誤，我感到非常抱歉。 我修改了代碼。 當類的setMethod接受基本類型參​​數時，會發生異常。

private static Object performMapping( Class voClass, Class[] clazz, Object voObject, Object data,String fieldType ){
    voClass.getMethod( "set" + fieldType, clazz ).invoke( voObject, data );
    return voObject;
}
private static Object mapField(ResultSet rs){
    Class voClass=Class.forName( "com.test.Test" );
    Object voObject = voClass.newInstance();
    Class[] doubleArrayParamTypes = new Class[ 1 ];
    doubleArrayParamTypes[ 0 ] = Double.class;
    voObject = performMapping( voClass, doubleArrayParamTypes, voObject, rs.getDouble(fieldType.getColumn()), "Mark" );
}
/* This is my Class. I need to set the Mark. But it is primitive double. Is it possible to set the mark using the above code? */
public class Test{
        private double mark;
        public double getMark() {
            return mark;
        }
        public void setMark(double mark) {
            this.mark = mark;

Answer 1

我所看到的是，您傳遞了setAddress1並將其與set連接起來，從而得到setsetAddress1 。 傳遞屬性名稱並將其大寫，或從串聯中刪除該set 。

同樣，您提供的代碼將無法編譯。 你不能有一個叫做class的變量

Answer 2

從臀部射擊，但是您不是要獲取setsetAddress1方法嗎？

（ "set" + methodName ）

Answer 3

下面的代碼有效。 您有兩個錯誤（語法上的類名錯誤除外）：

package com.test;

import java.io.IOException;
import java.lang.reflect.*;
import java.util.Arrays;

public class Test {

    Test() throws ClassNotFoundException, InstantiationException,
            IllegalAccessException, IllegalArgumentException,
            SecurityException, InvocationTargetException, NoSuchMethodException {

    }

    private void m() throws IllegalArgumentException, SecurityException, IllegalAccessException, InvocationTargetException, NoSuchMethodException, ClassNotFoundException, InstantiationException {

        Class[] doubleArrayParamTypes = new Class[1];
        doubleArrayParamTypes[0] = Double.class;
        Class clazz = Class.forName("com.test.Test");
        Object voObject = clazz.newInstance();
        Double data = 5.0;

        performMapping(clazz, "Address1", doubleArrayParamTypes, voObject, data);

    }

    public static void main(String... args) throws IOException,
            ClassNotFoundException, InstantiationException,
            IllegalAccessException, IllegalArgumentException, SecurityException, InvocationTargetException, NoSuchMethodException {
        new Test().m();
    }


    /* Reflection to set the data */
    @SuppressWarnings("unchecked")
    private void performMapping(Class clazz1, String methodName, Class[] clazz,
                                Object voObject, Double data)
            throws IllegalArgumentException, SecurityException,
            IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {
        for (Method m : clazz1.getMethods()) {
            System.out.println(m.getName()+ " " + Arrays.toString(m.getParameterTypes()));
        }
        clazz1.getMethod("set" + methodName, clazz).invoke(voObject, data);
    }

    public void setAddress1(Double arg) {
        System.out.println(arg);
    }
}

1. 正如其他作者所指出的，您在方法名稱中兩次添加了“ set”
2. 您嘗試傳遞String String data="TestData"; 作為參數，即使您指定該參數的類型應該為Double ： doubleArrayParamTypes[ 0 ] = Double.class;