java.util.Stack

Stack is a Last-In/First-Out(LIFO) data structure which represents a stack of objects. It enables users to pop to and push from the stack, including null objects. There is no limit to the size of the stack.

Example:

package com.AndroidStack;

import java.util.Stack;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidStackActivity extends Activity {
 
 EditText input;
 TextView content;
 Button push, pop;
 
 Stack<String> myStack;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        input = (EditText)findViewById(R.id.input);
     content = (TextView)findViewById(R.id.content);
     push = (Button)findViewById(R.id.push);
     pop = (Button)findViewById(R.id.pop);
     myStack = new Stack<String>();
     ShowContent();
     
     push.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    String pushItem = input.getText().toString();
    myStack.push(pushItem);
    Toast.makeText(AndroidStackActivity.this, 
      "push: " + pushItem, 
      Toast.LENGTH_LONG).show();
    ShowContent();
   }});
     
     pop.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    if(myStack.empty()){
     Toast.makeText(AndroidStackActivity.this, 
       "Empty!", 
       Toast.LENGTH_LONG).show();
    }else{
     String popItem = myStack.pop();
     Toast.makeText(AndroidStackActivity.this, 
       "pop: " + popItem, 
       Toast.LENGTH_LONG).show();
    }
    ShowContent();
   }});
    }
    
    void ShowContent(){
     if(myStack.empty()){
      content.setText("- Empty -");
     }else{
      String lastContent = "last content: " + myStack.peek();
      content.setText(lastContent);
     }
     
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<EditText
    android:id="@+id/input"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" />
<Button
    android:id="@+id/push"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="push" />
<Button
    android:id="@+id/pop"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="pop" />
<TextView
    android:id="@+id/content"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" />
</LinearLayout>

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