安卓日志猫的使用

package com.lidaochen.phonecall;

import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TabHost;
import android.widget.ThemedSpinnerAdapter;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity{
    public static final String tag = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.d(tag, "我是debug级别");
        Log.v(tag, "我是V级别");
        Log.i(tag, "我是info级别");
        Log.e(tag, "我是error级别");
        Log.w(tag, "我是warn级别");
        System.out.println("Hello World!");
    }
}