Android 泛型小例 findById

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package com.louisgeek.louisgenericstest;import android.app.Activity;import android.app.Dialog;import android.view.View;/** * 泛型自动类型自动推导 * 缺点 用的时候需要注意   类型与id类型是否真正对应 * Created by louisgeek on 2016/9/13. */public class ViewTool {    public static <V extends View> V findById(Activity activity, int resID){        return (V) activity.findViewById(resID);    }    public static <V extends View> V findById(View view, int id) {        return (V) view.findViewById(id);    }    public static <V extends View> V findById(Dialog dialog, int id) {        return (V) dialog.findViewById(id);    }}

package com.louisgeek.louisgenericstest;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.widget.TextView;public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        TextView textView=ViewTool.findById(this,R.id.id_tv);        textView.setText("zhuzhu");    }}

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