Category Archives: Java

Android getString(R.string.text) in a static method

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Sometimes there is a need to access recourses from static methods.
In order to do this we need to pass along the Context to the method and use getString from that Context.

Example:

package com.f15ijp.android.test;
 
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.WindowManager;
 
public class Help {
	public static AlertDialog helpDialog(Context theContext, String helpMessage){
	AlertDialog alertDialog = new AlertDialog.Builder(theContext).create();            	
    	alertDialog.setTitle("Help");
    	alertDialog.setMessage(helpMessage);
    	alertDialog.setButton(theContext.getString(R.string.close_help_btn), new DialogInterface.OnClickListener() {
	    @Override
	    public void onClick(DialogInterface dialog, int which) {
		return;						
	    }
	});
    	WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
        lp.copyFrom(alertDialog.getWindow().getAttributes());
        lp.width = WindowManager.LayoutParams.FILL_PARENT;
        lp.height = WindowManager.LayoutParams.FILL_PARENT;
        /*by calling alertDialog.show() now and then again after setAttributes the background
         * the background activity is replaced by a black box. 
         * If this first alertDialog.show() is removed then the (current) acitivity is used as a background. 
         */
        alertDialog.show();
        alertDialog.getWindow().setAttributes(lp);
        return alertDialog;
    }
}

Java iterating over a Map

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In java it is not hard to iterate over a Map. The following example is quick and simple (and if your Map is not of this sort you can change it accordingly easily).

for (Map.Entry<String, Object> entry : map.entrySet()) {
    String key = entry.getKey();
    Object value = entry.getValue();
    // ... do important stuff here!
}

Java Array toString

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Doing a toString on a array don’t really tell that much about the array. Here is one way to get the contents of the array as a string.

int[] myArray = new int[2];
myArray[0] = 1; myArray[1] = 2;
System.out.println("array contains " + java.util.Arrays.toString(myArray));
 
//will output array contains [1, 2]

Java Converting a int to a string

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The Integer Class have a static method toString that takes a int as input and gives us back a string.

int myInt = 1;
System.out.println(Integer.toString(myInt);

This is a log more efficient and nice in the long run than just concating the int with a empty string ( myInt + “” ) as that actually creates a bit of overhead. Not much, but still.

Java Converting between Boolean & String

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To convert from a Boolean to a string

new Boolean(new String("hej".equalsIgnoreCase("HEJ")).toString();

and then from a string to a boolean

boolean theValue = Boolean.parseBoolean(strBoolean);

Java safe conversion of long to int

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In most cases this is really not needed, if possible please keep the long as a long and work with it as such, but if needed the following works

public static int longToInt(long value) {
    if (value < Integer.MIN_VALUE || value > Integer.MAX_VALUE) {
        throw new IllegalArgumentException
            (value + " cannot be cast to int without changing its value.");
    }
    return (int) value;
}

The reason that theLong.intValue() is not suggested here is that intValue rounds the value to fit a int – it don’t say it can’t be done.

Setting up JAVA_HOME on Window

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The JAVA_HOME variable should point to the JDK’s bin folder in order for Java applications (jar, war, etc) to know where Java lives.

To setup a JAVA_HOME environment variable on Windows.

  • Right click on the My Computer icon in the start menu or on the desktop and select properties
  • Click the Advanced Tab
  • Click the Environment Variables button
  • Under System Variable, click New
  • Enter the variable name as JAVA_HOME
  • Enter the variable value as the install path for the Development Kit
  • Click OK
  • Click Apply Changes

Word of caution, Java is not fond of spaces, so I use pathnames without spaces.

Note: You will need to click OK, apply changes AND reload cmd to see the changes there.