java - 创建一个按钮并以编程方式将其添加到 View 中

Question

我正在创建流行的扫雷游戏的 Android 版本。我正在尝试以编程方式创建一个按钮并将其添加到relativelayout。我在这里发现了非常相似的东西:How do I programmatically add buttons into layout one by one in several lines?

当我尝试运行它时，我在以下位置收到 NullPointerException:

RelativeLayout layout1 = (RelativeLayout) findViewById(R.layout.game);

这是整个代码块:

public void create() {
    RelativeLayout layout1 = (RelativeLayout) findViewById(R.layout.game);
    for(int i = 0; i < gridSize; i++) {
        if(grid[i] == 0) { //if grid pos. indicates an empty cell
            Button empty = new Button(this);
            empty.setBackgroundResource(R.drawable.emptybutton); //set background to empty
            empty.setId(i); //set id to value of i
            empty.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            layout1.addView(empty); //add the button to the relativeLayout view
            //((Button) findViewById(i)).setOnClickListener(emptyListener); 
        }

提前感谢您的回复

Answer 1

已通过 setContentView(R.layout.xxxx) 设置 Activity 的布局 xml ？

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.game);


...

这个

 RelativeLayout layout1 = (RelativeLayout) findViewById(R.layout.game);

应该是

 RelativeLayout layout1 = (RelativeLayout) findViewById(R.id.relative_id);

R.id...用于映射控件，RelativeLayout是一个控件。