为什么 Activity 的构造函数中的 getApplicationContext() 会抛出空指针异常? [英] Why getApplicationContext() in constructor of Activity throws null pointer exception?

问题描述

经过一段时间的 bug 搜索，结果是:

After some time spent bug hunting it turns out that :

public class MainActivity extends BaseActivity { // BaseActivity extends Activity

    public MainActivity() {
        super();
        getApplicationContext(); // NPE here
    }
}

为什么?这是在哪里记录的?
弗罗约

Why ? Where is this documented ?
Froyo

推荐答案

等待 onCreate 结束调用此方法.

Wait for the end of onCreate to call this method.

public class MainActivity extends BaseActivity { 

    public onCreate(Bundle savedInstanceState) {
        super(savedInstanceState);
        getApplicationContext(); //activity has a context now
    }
}

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