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Population development

Java is the most populous major island in the world and is home to 56% of Indonesia's population, with a combined population of 156.4 million according to the official estimates as at mid 2023 (including Madura's 4.06 million). At nearly 1,185 people per km in 2023, it is also one of the most densely populated parts of the world, on a par with Bangladesh. Every region of the island has numerous volcanoes, with the people left to share the remaining flatter land. Because of this, many coasts are heavily populated and cities ring around the valleys surrounding volcanic peaks.

The population growth rate more than doubled in economically depressed Central Java in the latest 2010–2020 period vs 2000–2010, indicative of migration or other issues; there were significant volcanic eruptions during the earlier period. Approximately 45% of the population of Indonesia is ethnically Javanese, while Sundanese make a large portion of Java's population as well.

The western third of the island (West Java, Banten, and DKI Jakarta) has an even higher population density, of roughly 1,563 per square kilometre and accounts for most of the population growth of Java. It is home to three metropolitan areas, Greater Jakarta (with outlying areas of Greater Serang and Greater Sukabumi), Greater Bandung, and Greater Cirebon.

From the 1970s to the fall of the Suharto regime in 1998, the Indonesian government ran transmigration programs aimed at resettling the population of Java on other less populated islands of Indonesia. This program has met with mixed results, sometimes causing conflicts between the locals and the recently arrived settlers. Nevertheless, it has caused Java's share of the nation's population to progressively decline.

Jakarta and its outskirts, being the dominant metropolis, is also home to people from all over the nation. East Java is also home to ethnic Balinese, as well as large numbers of Madurans due to their historic poverty.