android11

뭔가 결과가 이상한데 이유를 모르겠다.

<!--main06.xml-->

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:id="@+id/baseLayout"
    >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="click"
        android:textSize="25dp"
        ></TextView>
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="click"
        android:textSize="25dp"
        android:background="@color/black"
        ></Button>
</LinearLayout>

<!--menu1.xml-->

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:id="@+id/baseLayout"
    >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="click"
        android:textSize="25dp"
        ></TextView>
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="click"
        android:textSize="25dp"
        android:background="@color/black"
        ></Button>
</LinearLayout>

package com.example.project1016_b;

import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Color;
import android.os.Bundle;
import android.view.MenuInflater;
import android.widget.Button;
import android.widget.LinearLayout;
import android.view.*;

import androidx.annotation.NonNull;

public class MainActivity extends AppCompatActivity {
    LinearLayout baseLayout;
    Button button1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main06);
        setTitle("배경색 바꾸기");
        baseLayout = (LinearLayout) findViewById(R.id.baseLayout);
        button1 = (Button) findViewById(R.id.button1);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        MenuInflater menuInflater = getMenuInflater();
        menuInflater.inflate(R.menu.menu1, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        if (item.getItemId() == R.id.itemRed) {
            baseLayout.setBackgroundColor(Color.RED);
            return true;
        } else if (item.getItemId() == R.id.itemGreen) {
            baseLayout.setBackgroundColor(Color.GREEN);
            return true;
        } else if (item.getItemId() == R.id.itemBlue) {
            baseLayout.setBackgroundColor(Color.BLUE);
            return true;
        } else if (item.getItemId() == R.id.subRotate) {
            button1.setRotation(45);
            return true;
        } else if (item.getItemId() == R.id.subSize) {
            button1.setScaleX(2);
            return true;
        }
        return false;
    }
}
/*package com.example.project1016_b;

import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LinearLayout baseLayout = new LinearLayout(this);

        baseLayout.setOrientation(LinearLayout.VERTICAL);

        LinearLayout.LayoutParams params=new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.MATCH_PARENT);

        baseLayout.setBackgroundColor(Color.rgb(0,255,0));
        setContentView(baseLayout);

        Button btn = new Button(this);
        btn.setText("버튼입니다");
        btn.setBackgroundColor(Color.MAGENTA);
        baseLayout.addView(btn);

        btn.setOnClickListener(new View.OnClickListener(){
            public void onClick(View arg0){
                Toast.makeText(getApplicationContext(), "코드로 생성한 버튼입니다", Toast.LENGTH_SHORT).show();
            }
        });
        //setContentView(R.layout.activity_main);
    }
}*/

암튼  MainActivity.java를 java만 써서 좀 더 쉬운코드로 변환해보자

package com.example.b1113;

import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Color;
import android.os.Bundle;
import android.view.MenuInflater;
import android.widget.Button;
import android.widget.LinearLayout;
import android.view.*;


public class MainActivity extends AppCompatActivity {
    LinearLayout baseLayout;
    Button button1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main01);
        setTitle("배경색 바꾸기");
        baseLayout = (LinearLayout) findViewById(R.id.baseLayout);
        button1 = (Button) findViewById(R.id.button1);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu){
        super.onCreateOptionsMenu(menu);
        menu.add(0,1,0,"배경색(빨강)");
        menu.add(0,2,0,"배경색(초록)");
        menu.add(0,3,0,"배경색(파랑)");
        
        SubMenu sMenu = menu.addSubMenu("버튼 변경>>");
        sMenu.add(0,4,0,"버튼 45도 회전");
        sMenu.add(0,5,0,"버튼 2배 확대");
        
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item){
        if (item.getItemId() == 1) {
            baseLayout.setBackgroundColor(Color.RED);
            return true;
        } else if (item.getItemId() == 2) {
            baseLayout.setBackgroundColor(Color.GREEN);
            return true;
        } else if (item.getItemId() == 3) {
            baseLayout.setBackgroundColor(Color.BLUE);
            return true;
        } else if (item.getItemId() == 4) {
            button1.setRotation(45);
            return true;
        } else if (item.getItemId() == 5) {
            button1.setScaleX(2);
            return true;
        }
        return false;
    }
}