android - 无法解析方法 getApplication()

Question

我在我的应用程序中创建了一个 Android 全局变量，当我尝试在我的 Activity 中使用 getApplication 访问它时，我收到错误:

Cannot resolve method getApplication()

我在扩展应用程序的类中的代码:

    package com.example.user.app;

    import android.app.Application;


    public class answer extends Application {

           private String answer1;

            public String getSomeVariable() {
                 return answer1;
              }

            public void setanswer1(String one) {
                this.answer1 = one;
                }
        }

我在 Activity 中的代码:

       package com.example.user.pilz_app;

       import android.content.Intent;
       import android.support.design.widget.FloatingActionButton;
       import android.support.design.widget.Snackbar;
       import android.support.v7.app.AppCompatActivity;
       import android.os.Bundle;
       import android.support.v7.widget.Toolbar;
       import android.view.View;
       import android.widget.ImageButton;

       public class QuestionOne extends AppCompatActivity {

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

            ImageButton half = findViewById(R.id.half);
            half.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
            Intent intent = new Intent(QuestionOne.this, QuestionTwo.class);
            startActivity(intent);
           ((answer) this.getApplication()).setanswer1("half");
           }

       });

Answer 1

您正在使用匿名类引用作为this

   half.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent intent = new Intent(QuestionOne.this, QuestionTwo.class);
                startActivity(intent);
                ((answer) this.getApplication()).setanswer1("half");
            }

请参阅 this，此时指向 OnClickListener 引用而不是您的 Activity。因此，您可以做的是使用如下完全限定的引用。

QuestionOne.this.getApplication().setanswer1("half");