java - 如何让Activity继承方法

Question

我有十几个 Activity 将继承密码键盘的相同方法。除了密码键盘之外，每个 Activity 都完全不同。如何让我的 Activity 继承公共(public)类的方法？我做错了什么吗？

public class TestActivity extends PinPadActivity {
    TextView mEntry;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);
        mEntry = (TextView) findViewById(R.id.entry_textview);
    }
}


public class PinPadActivity extends AppCompatActivity {
    String mPin;
    String mPinShow;
    TextView mEntry;
    public void on1Click(View v) {
        mPin = mPin+"1";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on2Click(View v) {
        mPin = mPin+"2";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on3Click(View v) {
        mPin = mPin+"3";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on4Click(View v) {
        mPin = mPin+"4";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on5Click(View v) {
        mPin = mPin+"5";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on6Click(View v) {
        mPin = mPin+"6";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on7Click(View v) {
        mPin = mPin+"7";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on8Click(View v) {
        mPin = mPin+"8";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on9Click(View v) {
        mPin = mPin+"9";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void on0Click(View v) {
        mPin = mPin+"0";
        mPinShow = mPinShow+"*";
        mEntry.setText(mPinShow);
    }
    public void onClearClick(View v) {
        mPin = "";
        mPinShow = "";
        mEntry.setText("");
    }
}

Answer 1

无论编码方式或是否是最佳方法，为了使您的代码正常工作，您应该删除 TestActivity 中的 TextView mEntry 并设置 public 或PinPadActivity 中 TextView mEntry 的 protected 修饰符(默认或私有(private)变量无法被子类访问)。这应该允许您调用 onXClick() 方法来设置从 TestActivity 中的 PinPadActivity 继承的 mEntry TextView 。