當我嘗試從自動完成文本獲取getText（）時，Android Prorgram崩潰

Question

我正在嘗試構建一個允許您輸入文本的android應用，然后將文本傳輸到主屏幕。 它使我可以毫無問題地構建自動完成功能，但是每當我嘗試調用getText（）函數時，整個程序就會崩潰。 任何幫助將不勝感激，謝謝

     public class TeamFragment extends DialogFragment {
TextView team1, team2, score1, score2;



    AutoCompleteTextView team1input;



public TeamFragment(View t1, View t2, View s1, View s2) {
    team1=(TextView) t1;
    team2=(TextView) t2;
    score1=(TextView) s1;
    score2=(TextView) s2;
}

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.team_score_layout, container);
    //mEditText = (EditText) view.findViewById(R.id.txt_your_name);
    getDialog().setTitle("Enter Team Name");
    Button b = (Button) view.findViewById(R.id.teamButton);

    b.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            team1input=(AutoCompleteTextView) v.findViewById(R.id.autoCompleteTeam1);
            team1input.getText();         //crashes here
            team1.setText("hi");
            dismiss();
        }
    });
    return view;
}


}

這是logCat，我似乎正在獲取nullpointerexception。

04-23 13:12:33.628: E/AndroidRuntime(902): FATAL EXCEPTION: main
04-23 13:12:33.628: E/AndroidRuntime(902): java.lang.NullPointerException
04-23 13:12:33.628: E/AndroidRuntime(902):  at com.example.ucsb.cs.cs185.dimberman.nba.TeamFragment$1.onClick(TeamFragment.java:42)
04-23 13:12:33.628: E/AndroidRuntime(902):  at android.view.View.performClick(View.java:2485)
04-23 13:12:33.628: E/AndroidRuntime(902):  at android.view.View$PerformClick.run(View.java:9080)
04-23 13:12:33.628: E/AndroidRuntime(902):  at android.os.Handler.handleCallback(Handler.java:587)
04-23 13:12:33.628: E/AndroidRuntime(902):  at android.os.Handler.dispatchMessage(Handler.java:92)
04-23 13:12:33.628: E/AndroidRuntime(902):  at android.os.Looper.loop(Looper.java:123)
04-23 13:12:33.628: E/AndroidRuntime(902):  at android.app.ActivityThread.main(ActivityThread.java:3683)
04-23 13:12:33.628: E/AndroidRuntime(902):  at java.lang.reflect.Method.invokeNative(Native Method)
04-23 13:12:33.628: E/AndroidRuntime(902):  at java.lang.reflect.Method.invoke(Method.java:507)
04-23 13:12:33.628: E/AndroidRuntime(902):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-23 13:12:33.628: E/AndroidRuntime(902):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-23 13:12:33.628: E/AndroidRuntime(902):  at dalvik.system.NativeStart.main(Native Method)

`

Answer 1

在onCreateView()方法中使用team1input = (AutoCompleteTextView) view.findViewById(R.id.autoCompleteTeam1) ，並在onClick()方法中刪除類似的行。

（假設您在team_score_layout.xml布局文件中定義了帶有autoCompleteTeam1 id的AutoCompleteTextView 。）

Answer 2

當您在視圖類下調用findViewById（）時，它將查找該類的子視圖。

觸發onClick時，傳遞給onClick() View v是按鈕。 如果您嘗試檢索的AutoCompleteView不是該按鈕的子項，則調用v.findViewById()將為您提供NullPointerException ，因為該視圖不存在於該按鈕的子項樹下。

Answer 3

只需更換

        team1input=(AutoCompleteTextView) v.findViewById(R.id.autoCompleteTeam1);

與

        team1input=(AutoCompleteTextView) view.findViewById(R.id.autoCompleteTeam1);