android中Menu的用法

最新推荐文章于 2019-01-21 10:34:33 发布

转载最新推荐文章于 2019-01-21 10:34:33 发布 · 620 阅读

本文介绍了一个使用Android API从XML文件中加载不同样式的上下文菜单的示例应用。该应用通过Spinner选择不同的菜单资源，并在Activity中动态加载对应的菜单布局。文章展示了如何通过Java代码实现菜单项的响应及可见性调整。

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package com.example.androidapi.menu;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.example.androidapi.R;

public class MenuInflateFromXml extends Activity {
	
    private static final int sMenuExampleResources[] = {
        R.menu.title_only, R.menu.title_icon, R.menu.submenu, R.menu.groups,
        R.menu.checkable, R.menu.shortcuts, R.menu.order, R.menu.category_order,
        R.menu.visible, R.menu.disabled
    };
    private static final String sMenuExampleNames[] = {
        "Title only", "Title and Icon", "Submenu", "Groups",
        "Checkable", "Shortcuts", "Order", "Category and Order",
        "Visible", "Disabled"
    };
   
    private Spinner mSpinner;
    private TextView mInstructionsText;
    private Menu mMenu;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, sMenuExampleNames); 
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        mSpinner = new Spinner(this);
        mSpinner.setId(R.id.spinner);
        mSpinner.setAdapter(adapter);
        
        layout.addView(mSpinner,
                new LinearLayout.LayoutParams(
                        LinearLayout.LayoutParams.MATCH_PARENT,
                        LinearLayout.LayoutParams.WRAP_CONTENT));

        mInstructionsText = new TextView(this);
        mInstructionsText.setText(getResources().getString(
                R.string.menu_from_xml_instructions_press_menu));
        
        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.WRAP_CONTENT);
        lp.setMargins(10, 10, 10, 10);
        layout.addView(mInstructionsText, lp);
        
        setContentView(layout);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        mMenu = menu;
        
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(sMenuExampleResources[mSpinner.getSelectedItemPosition()], menu);
        mSpinner.setEnabled(false);
        
        mInstructionsText.setText(getResources().getString(
                R.string.menu_from_xml_instructions_go_back));
        
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.jump:
                Toast.makeText(this, "Jump up in the air!", Toast.LENGTH_SHORT).show();
                return true;

            case R.id.dive:
                Toast.makeText(this, "Dive into the water!", Toast.LENGTH_SHORT).show();
                return true;

            case R.id.browser_visibility:
                final boolean shouldShowBrowser = !mMenu.findItem(R.id.refresh).isVisible();
                mMenu.setGroupVisible(R.id.browser, shouldShowBrowser);
                break;
                
            case R.id.email_visibility:
                final boolean shouldShowEmail = !mMenu.findItem(R.id.reply).isVisible();
                mMenu.setGroupVisible(R.id.email, shouldShowEmail);
                break;
                
            default:
                if (!item.hasSubMenu()) {
                    Toast.makeText(this, item.getTitle(), Toast.LENGTH_SHORT).show();
                    return true;
                }
                break;
        }
        
        return false;
    }
    
    

}