android Bitmap to File

android Bitmap to File


    case REQUEST_IMAGE_CAPTURE:
        File f = getFilesDir();
        Bitmap bit = data.getExtras().getParcelable("data");
        ImageView imageView = (ImageView) findViewById(R.id.bit);
        imageView.setImageBitmap(bit);

        try {
            FileOutputStream fileOutputStream = new FileOutputStream(f.getPath() + "/xxx.jpg");
            bit.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
            fileOutputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        break;

android 裁剪图片库图片

android 裁剪图片库图片

package com.kankanla.m0531a;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_IMAGE_SELECT = 1;
    private static final int REQUEST_IMAGE_CAPTURE = 2;

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

    protected void setCutimg() {
        Intent intent = new Intent();
        intent.setAction(intent.ACTION_OPEN_DOCUMENT);
        intent.setType("image/*");
        startActivityForResult(intent, REQUEST_IMAGE_SELECT);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            switch (requestCode) {
                case REQUEST_IMAGE_SELECT:
                    Intent intent = new Intent("com.android.camera.action.CROP");
                    Uri uri = data.getData();
                    intent.setData(uri);
                    intent.putExtra("outputX", 200);
                    intent.putExtra("outputY", 200);
                    intent.putExtra("aspectX", 1);
                    intent.putExtra("aspectY", 1);
                    intent.putExtra("scale", true);
                    intent.putExtra("return-data", true);
                    startActivityForResult(intent, REQUEST_IMAGE_CAPTURE);
                    break;
                case REQUEST_IMAGE_CAPTURE:
                    Bitmap bit = data.getExtras().getParcelable("data");
                    ImageView imageView = (ImageView) findViewById(R.id.bit);
                    imageView.setImageBitmap(bit);
                    break;
            }
        }
    }
}

Android 片段的生命周期（其 Activity 运行时）

片段的生命周期（其 Activity 运行时）

https://developer.android.com/guide/components/fragments.html

第一次启动
....m.out: Item_list--------------onAttach----------------
....m.out: Item_list--------------onCreate----------------
....m.out: Item_list--------------onCreateView----------------
....m.out: Item_list--------------onActivityCreated----------------
....m.out: Item_list--------------onStart----------------
....m.out: Item_list--------------onResume----------------


关闭屏幕
....nla.m0417b I/System.out: Item_list--------------onPause----------------
....nla.m0417b I/System.out: Item_list--------------onStop----------------

从新开屏幕
....nla.m0417b I/System.out: Item_list--------------onStart----------------
....nla.m0417b I/System.out: Item_list--------------onResume----------------



反转屏幕
....nla.m0417b I/System.out: Item_list--------------onPause----------------
....nla.m0417b I/System.out: Item_list--------------onStop----------------
....nla.m0417b I/System.out: Item_list--------------onDestroyView----------------
....nla.m0417b I/System.out: Item_list--------------onDetach----------------
....nla.m0417b I/System.out: Item_list--------------onAttach----------------
....nla.m0417b I/System.out: Item_list--------------onCreateView----------------
....nla.m0417b I/System.out: Item_list--------------onActivityCreated----------------
....nla.m0417b I/System.out: Item_list--------------onStart----------------
....nla.m0417b I/System.out: Item_list--------------onResume----------------


退回到上一Activety
....nla.m0417b I/System.out: Item_list--------------onPause----------------
....nla.m0417b I/System.out: Item_list--------------onStop----------------
....nla.m0417b I/System.out: Item_list--------------onDestroyView----------------
....nla.m0417b I/System.out: Item_list--------------onDestroy----------------
....nla.m0417b I/System.out: Item_list--------------onDetach----------------


从概览屏幕中返回
....nla.m0417b I/System.out: Item_list--------------onAttach----------------
....nla.m0417b I/System.out: Item_list--------------onCreate----------------
....nla.m0417b I/System.out: Item_list--------------onCreateView----------------
....nla.m0417b I/System.out: Item_list--------------onActivityCreated----------------
....nla.m0417b I/System.out: Item_list--------------onStart----------------
....nla.m0417b I/System.out: Item_list--------------onResume----------------

打开概览屏幕
....nla.m0417b I/System.out: Item_list--------------onPause----------------
....nla.m0417b I/System.out: Item_list--------------onStop----------------

打开其他Activety

在概览屏幕中删除
....m.out: Item_list--------------onDestroyView----------------
....m.out: Item_list--------------onDestroy----------------
....m.out: Item_list--------------onDetach----------------


按图标重新启动
....nla.m0417b I/System.out: Item_list--------------onAttach----------------
....nla.m0417b I/System.out: Item_list--------------onCreate----------------
....nla.m0417b I/System.out: Item_list--------------onCreateView----------------
....nla.m0417b I/System.out: Item_list--------------onActivityCreated----------------
....nla.m0417b I/System.out: Item_list--------------onStart----------------
....nla.m0417b I/System.out: Item_list--------------onResume----------------

Java interface Callback 2

Java interface Callback 2


import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws Exception{
        T1 t = new T1();
        try{
            Thread.sleep(1000);
        }catch(Exception e){
           
        }
        t.st();
    }
}

class T1 implements onTest{
    public Oset o;
    public T1(){
        o = new Oset();
        o.setont(this);
    }
   
    public void st(){
        o.methods();
    }
   
    public void getx(){
        System.out.println("--------implements onTest--------");
    }
}

interface onTest{
    public void getx();
}

class Oset {
    private onTest ont;
    public void setont(onTest ont){
        this.ont = ont;
    }
   
    public void methods(){
        System.out.println("--------------methods------------------");
        ont.getx();
    }
}


Demo
https://paiza.io/projects/l2lBiluXHzRmjoKsj-cLBA

Java interface Callback

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws Exception {
    Oset oset = new Oset();
    oset.setont(new onTest(){
        public void getx(){
            System.out.println("----------------interface Callback---------------");
        }
    });

    try{
        Thread.sleep(1000);
    }catch(Exception e){
     
    }
    oset.methods();
    }
}


interface onTest{
    public void getx();
}

class Oset {
    private onTest ont;
    public void setont(onTest ont){
        this.ont = ont;
    }
 
    public void methods(){
        System.out.println("--------------methods------------------");
        ont.getx();
    }
}

Demo
https://paiza.io/projects/uWqAgbv37VXi3LEWkS4WlQ

Thread.activeCount()

Thread.activeCount()

返回当前线程的线程组中活动线程的数目。

public class T2 {

        public static void main(String[] args) {

                new Thread(new Runnable() {

                        public void run() {

                                while (true) {

                                        // System.out.println(1);

                                }

                        }

                }).start();

                new Thread(new Runnable() {

                        public void run() {

                                while (true) {

                                        // System.out.println(2);

                                }

                        }

                }).start();

                new Thread(new Runnable() {

                        public void run() {

                                while (true) {

                                        // System.out.println(3);

                                }

                        }

                }).start();

                System.out.println(Thread.activeCount());

        }

}

Java ArrayList to String[]

Java ArrayList to String[]

https://paiza.io/projects/3F_iZEjxHh9AUNgPwAohxA

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class Main {
    public static void main(String[] args) throws Exception {
        ArrayList<String> sl = new ArrayList<String>();
        sl.add("a");
        sl.add("b");
        sl.add("c");
       
        String[] temp = sl.toArray(new String[]{});
       
        System.out.println(temp.length);
        for( String x:temp){
            System.out.println(x);
        }
    }
}