我的开发笔记

1.Android中的Toast是一种简易的消息提示框。

使用需引入包：

import android.widget.Toast;

Toast.makeText(this,"red",Toast.LENGTH_LONG).show();

2.关联布局

新建xml-》layout xml - > setContentView(R.layout.yflayout);

3根据id获取一个控件添加点击事件第一种

Button yfcBtn = findViewById(R.id.buttonyfc);

yfcBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        System.out.println("cvbnmsdfghj");
        Toast.makeText(MainActivity.this,"hhhh",Toast.LENGTH_LONG).show();;
    }
});

4设置控制台输出过滤器

edit filter config -> log tag - >System.out

5 点击事件第二种

yfcBtn.setOnClickListener(new MyclickListener());

class  MyclickListener implements  View.OnClickListener{
    @Override
    public  void onClick(View view){
        System.out.println("cvbnmsdfghj");
        Toast.makeText(MainActivity.this,"hhkhh",Toast.LENGTH_LONG).show();;

    }

}

//第三种

public class MainActivity extends AppCompatActivity implements View.OnClickListener 
yfcBtn.setOnClickListener(this);

    @Override
    public void onClick(View v) {
                System.out.println("cvbnmsdfghj");
        Toast.makeText(MainActivity.this,"hhggkhh",Toast.LENGTH_LONG).show();;
//
    }

第一种和第三种使用最多

第四种

<Button
    android:id="@+id/buttonyfc"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:onClick="onClickyyy"
    android:text="Button" />

public  void  onClickyyy(View  view){

    System.out.println("cvbnmsdfghj");
    Toast.makeText(MainActivity.this,"hhkhh",Toast.LENGTH_LONG).show();;

}
6.布局  类型

ConstraintLayout

LinearLayout

7输入框

EditText textFiled = findViewById(R.id.editTextyfc);

8全局

private EditText textFiled;

9打电话

<uses-permission android:name="android.permission.CALL_PHONE"/>

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

   if (requestCode == 1){
       if (grantResults[0] == PackageManager.PERMISSION_GRANTED){
           callph0ne();;
       }else {

       }
   }


    super.onRequestPermissionsResult(requestCode, permissions, grantResults);


}

if(text.equals("")){
    Toast.makeText(MainActivity.this,"号码",Toast.LENGTH_LONG).show();
}else {
    //创建意图
    Intent intent = new Intent();
    //创建动作
    intent.setAction(Intent.ACTION_CALL);
    //动作的数据
    intent.setData(Uri.parse("tel://"+ text));
    //开启界面
    startActivity(intent);

}

10线性布局相对布局帧布局表格布局绝对布局（少）约束布局

11安卓里的textview就是ios里的UILabel

PlainText 相当于ios里的 UITextFiled

hint相当于placeHolder

MultilineText 相当于 UITextView

12 添加新类

<activity android:name=".BaseActivity"/>

BaseActivity运行时权限轮子

public class MainActivity extends BaseActivity

final String phoneNum

13先写变量然后再自动生成声明代码 ALT+Enter

private static final String TAG = "MMMM";

Log.v(TAG,"v级别");
Log.d(TAG,"D级别");
Log.i(TAG,"i级别");
Log.w(TAG,"w级别");
Log.e(TAG,"e级别");

14局部邊全部 alt cmd f

TextUtils.isEmpty(qq) 文本框空

讀寫文件

try {
            //寫文件
    File file =  new File(this.getFilesDir(),"info.txt");

    FileOutputStream outS = new FileOutputStream(file);

    String info = "hhh" + "#hhhj";
    outS.write(info.getBytes());
    outS.close();;



    //讀
    if(file.exists() && file.length() > 0){
        FileInputStream fis = new FileInputStream(file);
        BufferedReader br = new BufferedReader(new InputStreamReader(fis));

        String str =   br.readLine();
        String qqqq = info.split("#")[0];
        qqno1.setText(qqqq);
    }

}catch (Exception e){

}

16获取存储空间方法不准

long datasize = dataFile.getTotalSpace();

 long sdsize = sdFile.getTotalSpace();

 //相当于nsuserDefault
SharedPreferences sp = getSharedPreferences("config",MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();;
editor.putBoolean("status",true);
editor.commit();

sp.getBoolean("

status",false);