java - Performclick() 期间出现 NullPointerException

Question

我正在对一项 Activity 进行单元测试。我的 Activity 有一个调用简单方法的按钮(没有 Activity 、服务或其他任何内容)。

java.lang.NullPointerException at com.android.my.test.MyActivityTest.testPerformClick(MyActivity.java:41) at java.lang.reflect.Method.invokeNative(Native Method) at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:205) at android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:195) at android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:175) at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:169) at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:154) at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:430) at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1447)

我的测试是这样的:

public class MyActivityTest extends ActivityInstrumentationTestCase2<MyActivity> {
    MyActivity a;

    public MyActivityTest() {
        super("com.android.my", MyActivity.class);
    }

    @Override
    public void setUp() throws Exception {
        super.setUp();
        a = this.getActivity();
    }

    @Override
    public void tearDown() throws Exception {
        super.tearDown();
    }

    public void testPerformClick() {
        a.getButton().performClick();
    }

}

我的 Activity 是这样的。

public class MyActivity extends Activity implements OnClickListener {

    private Button b;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        button = new Button();
        button.setOnClickListener(this);
    }

    @Override
    public void onClick(View arg0) {
        method();
    }

    private void method() {
        // [...]
    }

    public void getButton() {
        return button();
    }
}

Answer 1

我的猜测是您需要将 MyActivity 更改为此。您的测试得到的方法 getButton()

为 NULL

public class MyActivity extends Activity implements OnClickListener 
{
    private Button b;

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        b=new Button();
        b.setOnClickListener(this);
    }

    @Override
    public void onClick(View arg0) 
    {
        method();
    }

    private void method()
    {
        ...
    }

    public Button getButton()
    {
        return b;
    }
}