android - 按下设备后退按钮时如何清除数据？

Question

我有这种代码，但它似乎不起作用

public static class DeleteDir {

    public static void main(String args[]) {
        deleteDirectory(new File(args[0]));
    }

    static public boolean deleteDirectory(File path) {
        if (path.exists()) {
            File[] files = path.listFiles();
            for (int i = 0; i < files.length; i++) {
                if (files[i].isDirectory()) {
                    deleteDirectory(files[i]);
                } else {
                    files[i].delete();
                }
            }
        }
        return (path.delete());
    }
}

public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        Intent intent = new Intent(getApplicationContext(),
                TeacherSide.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);
        finish();
    }
    return super.onKeyDown(keyCode, event);
}

谁能帮我解决这个问题？

Answer 1

试试这个:

@Override
public void onBackPressed() 
{
    Intent intent = new Intent(getApplicationContext(),PreviousActivity.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    intent.putExtra("EXIT", true);
    startActivity(intent);
    finish();
}

如果这是最后一个 Activity 或有任何 PreviousActivity ，则将此代码放在 setContentView()

之前

if (getIntent().getBooleanExtra("EXIT", false)) {
    finish();
}           
setContentView(R.layout.main);

通过这种方式可以清除数据。