MainActivity.java

package com.example.le.myapplication;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    public static int MA_TRA_VE = 912; // cai nay dat the nao cung duoc
    TextView tvFile;
    Button btnPick;

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

        tvFile = (TextView) findViewById(R.id.textView);
        btnPick = (Button) findViewById(R.id.button);


        btnPick.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                intent.setType("*/*");
                startActivityForResult(intent, MA_TRA_VE );
            }
        });

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if ( requestCode == MA_TRA_VE ){
            // data la file ma minh vua chon. Sau do dung duong dan cua no de
            // su dung vao muc dich cua minh
            Uri fileVuaChon = data.getData();
            tvFile.setText(fileVuaChon.toString());
        }
    }
}