所有的Android中的控制元件都是繼承於View，ViewGroup也不例外。在ViewGroup中有個addView的方法能動態的新增一個子view。

這個是一個簡單的例子，能在程式碼中動態的新增一個子view：

示例圖片：

package com.example.foreveross.myapplication;


import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.RecyclerView;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private LinearLayout mLay;
    private Button mBtn1;
    private Button mBtn2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initData();
        initEvent();
    }

    private void initEvent() {
        mBtn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mBtn2.setBackgroundColor(Color.RED);
            }
        });
    }

    private void initData() {
        TextView tv = new TextView(this);
        tv.setText("動態新增的");
        tv.setGravity(Gravity.CENTER);
        tv.setTextSize(20);
        LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        mLay.addView(tv, layoutParams);
    }

    private void initView() {
        mLay = (LinearLayout) findViewById(R.id.llay);
        mBtn1 = (Button) findViewById(R.id.btn1);
        mBtn2 = (Button) findViewById(R.id.btn2);
    }

}
 

1.關於ViewGroup的原始碼也翻看了一些：

 關於addView有下面幾種方法過載：

   1.直接傳入一個view進行新增：

 public void addView(View child) {
        addView(child, -1);  
    }

 public void addView(View child, int index) {
        if (child == null) {
            throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
        }
        LayoutParams params = child.getLayoutParams();  //獲取子view的layout引數
        if (params == null) {
            params = generateDefaultLayoutParams();
            if (params == null) {
                throw new IllegalArgumentException("generateDefaultLayoutParams() cannot return null");
            }
        }
        addView(child, index, params);
    }
 

public void addView(View child, int width, int height) {
        final LayoutParams params = generateDefaultLayoutParams();
        params.width = width;
        params.height = height;
        addView(child, -1, params);
    }

public void addView(View child, LayoutParams params) {
        addView(child, -1, params);
    }
 

public void addView(View child, int index, LayoutParams params) {
        if (DBG) {
            System.out.println(this + " addView");
        }

        if (child == null) {
            throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");
        }

        // addViewInner() will call child.requestLayout() when setting the new LayoutParams
        // therefore, we call requestLayout() on ourselves before, so that the child's request
        // will be blocked at our level
        requestLayout();    //當view的佈局失效改變時會呼叫這個，它會按規則重新佈局view的樹（view tree）
        invalidate(true);
        addViewInner(child, index, params, false);   //call子view
    }

所以當加入子view時必須設定LayoutParams的值，對於LayoutParams只是傳入子view的寬高和位置的資訊：

public LayoutParams(Context c, AttributeSet attrs);   //傳入xml檔案中設定的屬性值，存於R檔案中

public LayoutParams(int width, int height);          //直接傳入寬高的值

public LayoutParams(LayoutParams source)              //傳寬高的source值

protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr);   //佈局setLayoutDimension之後的寬高值
在這裡有一個MarginLayoutParams是繼承於LayoutParams的，能在這裡設定Margin的值