android背面按下了

Question

@Override
public void onBackPressed(){
    if (back_pressed + 2000 > System.currentTimeMillis()){
        Homepage1.super.onBackPressed();
    }
    else{
        Toast.makeText(getBaseContext(), "Press once again to exit", Toast.LENGTH_SHORT).show();
        back_pressed = System.currentTimeMillis();
    }
}

  

错误：（51,42）错误：';'预期错误：任务执行失败   '：应用程序：compileDebugJavaWithJavac'。编译失败;看到编译器   错误输出以获取详细信息。

Answer 1

将此方法放在Activity类中。

public class MyActivity extends AppCompatActivity {

    @Override
    public void onBackPressed() {
        if (back_pressed + 2000 > System.currentTimeMillis()){
                    Homepage1.super.onBackPressed();
                }
                else{
                    Toast.makeText(getBaseContext(), "Press once again to exit", Toast.LENGTH_SHORT).show();
                    back_pressed = System.currentTimeMillis();
                }
    }
}