Question

我目前正在按照教程实现一个搜索栏来过滤我的listView，我的课程是这样的：

package com.example.fragmenttabhostdemo;

import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;

public class Tab1 extends Fragment {

    private ListView lv;
    private EditText et;
    private String listview_array[] = { "ONE", "TWO", "THREE", "FOUR", "FIVE",
            "SIX", "SEVEN", "EIGHT", "NINE", "TEN" };
    private ArrayList<String> array_sort= new ArrayList<String>();
    int textlength=0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

         //lv = (ListView) getView().findViewById(R.id.ListView01);
        //et = (EditText) getView().findViewById(R.id.EditText01);
        //lv.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_list_item_1, listview_array));
     }

问题是，一旦我删除了最后一行中的coments（“//”），这些应用程序就不起作用......它说：

06-11 12:06:37.964: D/AndroidRuntime(3101): Shutting down VM
06-11 12:06:37.964: W/dalvikvm(3101): threadid=1: thread exiting with uncaught exception (group=0xb1a17ba8)
06-11 12:06:37.984: E/AndroidRuntime(3101): FATAL EXCEPTION: main
06-11 12:06:37.984: E/AndroidRuntime(3101): Process: com.example.fragmenttabhostdemo, PID: 3101
06-11 12:06:37.984: E/AndroidRuntime(3101): java.lang.NullPointerException
06-11 12:06:37.984: E/AndroidRuntime(3101):     at com.example.fragmenttabhostdemo.Tab1.onCreateView(Tab1.java:34)

我只是觉得使用这些变量是一个问题，但是，这个......或者将私密性从公用变为公用，都没有用。

一周前我开始学习android java，所以我真的很棒。

TY

P.S。返回缺失，因为评论下面有很多代码，但我省略了它只是为了保持简单。（对不起）

Answer 1

检查此方法：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
 }

此方法的返回类型为View。在这里你应该膨胀适当的xml布局。所以改成它：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.my_fragment,container,false);
//this is how you use findviewbyid inside fragment
Button myBut = (Button) view.findViewById(R.id.buttonMyBut);
return view;
 }

Answer 2

问题是您实际上从未真正为Fragment设置视图。您无法在getView()方法中调用onCreateView()。相反，您应该执行以下操作。

@Override
public View onCreateView(LayoutInflater inflater, 
    ViewGroup container, Bundle savedInstanceState) {

    // This is where you actually get your view.  
    // Replace R.layout.fragment_layout with the layout file you are using 
    View myView = inflater.inflate(R.layout.fragment_layout, container, false);

    // Now you can call findViewById on your newly inflated view
    lv = (ListView) myView.findViewById(R.id.ListView01);
    et = (EditText) myView.findViewById(R.id.EditText01);
    lv.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(),
        android.R.layout.simple_list_item_1, listview_array));

    // Be sure to return the view!
    return myView;
}

扩展Fragment类变量，不起作用

2 个答案: