java编辑文本。GetText，返回关于null引用的异常，但已声明该异常

Question

我正在开发一个Android应用程序，我遇到了一些问题

我有一些EditText输入，我想用输入的文本创建一个名为Contest的对象。我的代码如下：

package com.example.torge.projectnow.loginSystem;

import 安卓.app.AlertDialog;
import 安卓.content.Intent;
import 安卓.os.Bundle;
import 安卓.support.design.widget.FloatingActionButton;
import 安卓.support.design.widget.Snackbar;
import 安卓.support.v7.app.AppCompatActivity;
import 安卓.support.v7.widget.Toolbar;
import 安卓.view.View;
import 安卓.widget.Button;
import 安卓.widget.EditText;
import 安卓.widget.Spinner;

import com.example.torge.projectnow.R;

public class AddContest extends AppCompatActivity implements View.OnClickListener{

    Spinner sCategoryC = null;
    String idUserUpload = "1";
    EditText etContestName, etShorDesC, etDeadlineC, etAgeLimitC, etStartDateC, etLocatoinC, etFullDesC, etCostC;
    UserLocalStore userLocalStore;
    Button bSendContest;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_contest);
        sCategoryC = (Spinner) findViewById(R.id.sCategoryContest);
        etContestName = (EditText) findViewById(R.id.etContestName);
        etShorDesC = (EditText) findViewById(R.id.etShortDesC);
        etDeadlineC = (EditText) findViewById(R.id.etDeadlineC);
        etAgeLimitC = (EditText) findViewById(R.id.etAgeLimitC);
        etStartDateC = (EditText) findViewById(R.id.etStartDateC);
        etFullDesC = (EditText) findViewById(R.id.etFullDescC);
        etCostC = (EditText) findViewById(R.id.etCostC);



        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton bSendContest = (FloatingActionButton) findViewById(R.id.bSendContest);
        bSendContest.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Contest contest = new Contest(etContestName.getText().toString(),
                        sCategoryC.getSelectedItem().toString(),
                        etShorDesC.getText().toString(),
                        etDeadlineC.getText().toString(),
                        etAgeLimitC.getText().toString(),
                        etStartDateC.getText().toString(),
                        etLocatoinC.getText().toString(),
                        etFullDesC.getText().toString(),
                        idUserUpload,
                        etCostC.getText().toString());

                switch (v.getId()){
                    case R.id.bSendContest :
                        if(etContestName.getText().toString().matches("") ||
                                sCategoryC.getSelectedItem().toString().matches("") ||
                                etShorDesC.getText().toString().matches("") ||
                                etDeadlineC.getText().toString().matches("") ||
                                etAgeLimitC.getText().toString().matches("") ||
                                etStartDateC.getText().toString().matches("") ||
                                etLocatoinC.getText().toString().matches("") ||
                                etFullDesC.getText().toString().matches("") ||
                                idUserUpload.matches("") ||
                                etCostC.getText().toString().matches("")){
                            AlertDialog alertDialog = new AlertDialog.Builder(AddContest.this).create();
                            alertDialog.setTitle("Something went wrong");
                            alertDialog.setMessage("Please fill all the boxes");
                            alertDialog.show();

                        }else {
                            ServerRequest serverRequest = new ServerRequest(AddContest.this);
                            serverRequest.StoreContestInBackground(contest);
                            Snackbar.make(findViewById(R.id.addProjectLayout), "The contest Succesfuly added!", Snackbar.LENGTH_LONG)
                                    .setAction("Action", null).show();
                            startActivity(new Intent(AddContest.this, Dashboard.class));
                        }

                        break;
                }
            }
        });
    }


    @Override
    public void onClick(View v) {


    }
}

但是我得到了这个错误

02-29 20:15:49.950 12260-12260/com.example.torge.projectnow E/AndroidRuntime: FATAL EXCEPTION: main
                                                                              Process: com.example.torge.projectnow, PID: 12260
                                                                              java.lang.NullPointerException: Attempt to invoke virtual method '安卓.text.Editable 安卓.widget.EditText.getText()' on a null object reference
                                                                                  at com.example.torge.projectnow.loginSystem.AddContest$1.onClick(AddContest.java:47)
                                                                                  at 安卓.view.View.performClick(View.java:4788)
                                                                                  at 安卓.view.View$PerformClick.run(View.java:19965)
                                                                                  at 安卓.os.Handler.handleCallback(Handler.java:739)
                                                                                  at 安卓.os.Handler.dispatchMessage(Handler.java:95)
                                                                                  at 安卓.os.Looper.loop(Looper.java:135)
                                                                                  at 安卓.app.ActivityThread.main(ActivityThread.java:5431)
                                                                                  at java.lang.reflect.Method.invoke(Native Method)
                                                                                  at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                  at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:914)
                                                                                  at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:707)

我无法解决它。你能帮我吗

Answer 1

您尚未初始化etLocatoinC

即

etLocatoinC=(EditText) findViewById(R.id.etLocatoinC);

您正试图对其调用getText（）方法

Answer 2

您忘记在onCreate方法中强制转换TextView etLocatoinC，该方法已声明，但引用为空。。。 由于您在onClick方法中调用getText，那么您将得到一个NPE

快速修复：

etLocatoinC=(EditText) findViewById(R.id.etLocatoinC);