Question

所以我制作了一个应用程序，您可以在其中输入一个片段上的按钮信息，然后将信息发送回活动，并将该片段替换为另一个片段，该片段将显示从第一个片段中检索到的信息。但是，我收到一个错误：＆＃34; com.example.cribbage2.CardKeyboardFrag无法强制转换为com.example.cribbage2.PCResultsFrag＆＃34;而且我不知道为什么。

以下是活动的相关代码：

package com.example.cribbage2;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.os.Bundle;

import java.util.Arrays;

public class PointCalculator extends FragmentActivity implements CardKeyboardFrag.InfoTransfer {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_point_calculator);

    //set cardKeyboardFrag
    CardKeyboardFrag cardFrag = new CardKeyboardFrag();
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.add(R.id.fragment_container, cardFrag);
    transaction.addToBackStack(null);
    transaction.commit();

    //tell fragment how many cards you are requesting
}

public void cardNumSet(int cardNumMin, int cardNumMax){
    CardKeyboardFrag cardKeyboardFrag = (CardKeyboardFrag) getSupportFragmentManager().findFragmentById(R.id.fragment_container);
    cardKeyboardFrag.cardNumGet(cardNumMin, cardNumMax);
}

public void displayResults(int[] resultsIntArray){

    //parse intArray into String
    String[] resultsStringArray = new String[4];
    int loop = 0;
    for (int num: resultsIntArray){
        resultsStringArray[loop] = Integer.toString(num);
        loop++;
    }

    //transfer to new fragment
    PCResultsFrag resultsFrag = new PCResultsFrag();
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.fragment_container, resultsFrag);
    transaction.addToBackStack(null);
    transaction.commit();


    //this is the line where the error occurs 
    PCResultsFrag pcResultsFrag = (PCResultsFrag) getSupportFragmentManager().findFragmentById(R.id.fragment_container);

    pcResultsFrag.getResultsArray(resultsStringArray);
}

Answer 1

尝试按照以下方式进行交易：

 transaction.replace(R.id.fragment_container, resultsFrag , "resultsFrag");

然后像这样得到片段的对象：

 Fragment currentFragment = getSupportFragmentManager().findFragmentByTag("resultsFrag");

 currentFragment.getResultsArray(resultsStringArray);

Answer 2

您在findFragmentById中引用的资源ID是针对片段容器视图而不是相关片段。

bagof/3

和

PCResultsFrag pcResultsFrag = (PCResultsFrag) getSupportFragmentManager().findFragmentById(**R.id.fragment_container**);

＆＃34;不能被投射到＆＃34;碎片异常

2 个答案: