Question

我有一个 Drawscreen.class 文件，主要活动和 Drawthegraph.class 扩展了视图。我在 Drawthegraph.class 中有一个方法，我需要从 Drawscreen.class 调用。我可以这样做吗？的 Drawscreen.class -

public class Drawscreen extends ActionBarActivity 
{

//LinearLayout linear=(LinearLayout)findViewById(R.id.main_layout);
//draw=(Drawthegraph)findViewById(R.id.main_layout);

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
    getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
    ActionBar actionbar=getSupportActionBar();
    actionbar.show();
    View drawthegraph=new Drawthegraph(this);
    setContentView(drawthegraph);
    drawthegraph.setBackgroundColor(color.Ivory);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) 
{
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.drawscreen, menu);
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) 
{
    switch (item.getItemId()) 

        case R.id.undo:/*Call method of view here*/
                        break;
    }
    return super.onOptionsItemSelected(item);
}   
}

Drawthegraph.class

public class Drawthegraph extends View
{
 private int lines; 
 ----
 ----
 public void decrease_lines() /*Call this function from Drawscreen*/
{
    if(lines>0)
    {
        lines--;
    }   
}

Answer 1

将drawthegraph变量用作实例字段：

public class Drawscreen extends ActionBarActivity 
{

//LinearLayout linear=(LinearLayout)findViewById(R.id.main_layout);
//draw=(Drawthegraph)findViewById(R.id.main_layout);

private Drawthegraph drawthegraph;

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
    getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
    ActionBar actionbar=getSupportActionBar();
    actionbar.show();
    this.drawthegraph=new Drawthegraph(this);
    setContentView(drawthegraph);
    drawthegraph.setBackgroundColor(color.Ivory);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) 
{
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.drawscreen, menu);
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) 
{
    switch (item.getItemId()) 

        case R.id.undo:/*Call method of view here*/
            drawthegraph.decrease_lines();
                        break;
    }
    return super.onOptionsItemSelected(item);
}   
}

Answer 2

您的Drawthegraph对象必须是您的Activity的字段：

public class Drawscreen extends ActionBarActivity {

    Drawthegraph drawthegraph;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        ...
        drawthegraph = new Drawthegraph(this);
        setContentView(drawthegraph);
        drawthegraph.setBackgroundColor(color.Ivory);
    }
    ...

然后你可以在Drawscreen中的任何地方打电话：

drawthegraph.decrease_lines();

从Activity访问View类的int数据

2 个答案: